Practical Guide to Selecting Rare-Earth Salt Systems and Key Points for Separation & Purification: A Hands-On Navigation for the Rare-Earth Permanent-Magnet Mainline and Magnet Recycling/Regeneration (with Product Tables A–E)

I.Background and Basic Concepts

1.1 | The real-world question: Why have rare earths become a key variable in the permanent-magnet value chain?

1. In applications such as wind turbines and EV traction motors, higher power density, lightweighting, and efficiency gains often rely on high-performance permanent magnets (typically rare-earth permanent-magnet systems). The reason the solution often points to rare-earth magnets is straightforward: improving power density and efficiency requires a higher and stable magnetic flux density. Permanent-magnet motors avoid continuous excitation losses, and rare-earth magnets such as Nd–Fe–B, with their high maximum energy product (BHmax) and high power density, are among the most representative high-performance permanent-magnet systems in engineering practice. For this very reason, growing magnet demand pushes the challenge from “having ore” to “element-level controllable supply,” making separation and purification the key upstream foundation.

2. Demand for permanent magnets shifts the rare-earth challenge from “mining” to “processing.” The reason is specific: it is not enough for a magnet to merely “contain rare earths”—it requires a single, stable, and controllable supply of specific rare-earth elements (e.g., primarily Nd/Pr, and in some systems also Dy/Tb, which are more critical for high-temperature demagnetization resistance). Once the feedstock must be “element-level controllable,” the bottleneck that determines supply capability and cost structure naturally falls on separation and purification.

3. This also explains why recent policy and industry discussions often mention “permanent magnets” together with “processing/recycling”: as magnet demand grows, the most sensitive capacity constraints are often in separation/refining and regeneration capability.

1.2 | How are rare earths, rare-earth salts, oxides, and magnets related?

Term	Intuitive definition (from an application-chain perspective)	Role in “permanent magnets—separation & purification”
Rare-earth elements (REEs)	A set of elements: typically the 15 lanthanides + scandium (Sc) + yttrium (Y), 17 in total	The targets “to be separated” and “to be purified”
Rare-earth ores / mixed rare earths	In nature, rare earths commonly co-occur and are associated with one another	The “natural form” is typically a mixture
Rare-earth salts (rare-earth salts)	Salts formed by rare-earth ions with anions (commonly chlorides, nitrates, sulfates, acetates, etc.; often hydrates/coordination forms)	The primary working medium for separation and purification (salt solutions / salt systems)
Rare-earth precipitation intermediates	e.g., oxalates/carbonates and other filterable solids	Used to convert “rare-earth ions in solution” into separable solids
Rare-earth oxides (REO)	One of the common industrial product forms (can be further converted to metals/alloys)	Often used as precursors to metals and magnetic materials
Rare-earth metals / alloys	Obtained via further reduction/electrolysis from oxides or salts	Enters magnet fabrication and alloying stages
Rare-earth permanent magnets	Rare-earth elements impart key properties such as high magnetocrystalline anisotropy	The end-use side imposes the strongest constraints on “high purity” and “controllability”

1.3 | What is a “rare-earth salt,” and why is it so critical in the value chain?

1. Rare-earth salts are an “engineering form” that makes rare-earth ions quantifiable, soluble, and transformable—allowing rare earths to enter solution-based separation/purification routes and downstream materials-synthesis pathways.

2. By way of example: most lanthanides exist predominantly as trivalent ions Ln³⁺ under common chemical conditions. Accordingly, rare-earth salts are often ionic compounds composed of Ln³⁺ and anions (Cl⁻, NO₃⁻, SO₄²⁻, OAc⁻, etc.), and they frequently feature hydration/coordination structures.

3. Note: rare earths are not exclusively +3. Ce more readily appears as +4 (especially under oxidizing conditions); Eu and Yb can appear as +2 under certain reducing conditions and/or coordination environments. Some rare earths can form non-trivalent states, but in typical aqueous separation operations, Ln³⁺ still dominates.

1.4 | Why is rare-earth separation difficult? Similarity leads to low separation factors (the underlying reason)

The fundamental reason rare-earth separation is challenging is:

1. The chemical properties of neighboring elements are highly similar. A classic cause is the lanthanide contraction: from La to Lu, atomic/ionic size decreases systematically as atomic number increases, but the differences between adjacent elements are small—resulting in low separation factors and forcing processes to be scaled into multi-stage operations.

2. Therefore, industrial separation commonly relies on solvent extraction: leveraging extractant selectivity and using multi-stage cascades to progressively amplify the small differences between neighboring rare earths. Engineering practice often strings together many extraction “stages”; each stage typically consists of a mixing–settling unit (first mix the two phases to reach distribution equilibrium, then allow phase disengagement and separation). To reach the target purity, dozens to over a hundred stages may be required, depending on the element set and purity specifications.

II.How to Choose Common Salt Systems

2.1 | The “process meaning” of rare-earth salt systems in separation and purification

Salt system (representative)	Typical position in separation & purification	Advantages	Points to watch
Chloride system (LnCl₃)	One of the common feed/solution forms (compatible with extraction flowsheets)	Typically good solubility and solution operability; convenient for bringing rare earths into a solution-based separation platform	Cl⁻ may be sensitive for certain downstream steps/equipment/systems; manage anion carryover/residuals within the process
Nitrate system (Ln(NO₃)₃)	One of the common feed/solution forms (also widely used for separation and as materials precursors)	Relatively “general-purpose” and compatible with many hydrometallurgical flows; also commonly used as precursor sources for materials synthesis	Manage acidity and side-reaction windows; also control anion carryover and risks of co-extraction/co-precipitation of impurities
Sulfate system (Ln₂(SO₄)₃)	Used in certain flows for conversion/segmentation or steps tied to impurity behavior	Under specific conditions, can assist with fractionation and impurity management (depending on process design)	SO₄²⁻ alters complexation/extraction behavior and can readily cause scaling and parasitic precipitation; sulfate leach liquors often require system conversion or condition control before high-purity extraction to match the extraction window
Acetate / organic acid salts (Ln(OAc)₃, etc.)	More oriented toward materials-synthesis precursor systems (tunable coordination/solvents); often used for sol–gel, complexation solutions, and dopant-precursor preparation	Solubility and coordination environment can be tuned via anion and solvent choice; not a commonly used carrier salt in industrial rare-earth separation	Not typical as the “main industrial separation platform”; the main separation route usually prioritizes chloride/nitrate systems

III.Using Spent NdFeB Permanent Magnets as an Example: The Key Roles and Pain Points of Rare-Earth Salts in the “Recycling–Regeneration” Chain

Along the permanent-magnet mainline, the most important significance of “rare-earth salts” is that they take on two critical jobs:

1. Bringing rare earths from solid magnets into a separable solution platform (forming a rare-earth salt solution);

2. Completing element-level splitting and purification in solution, then converting the products back into usable solid precursors (precipitated salts/oxides), providing a starting feedstock for remanufacturing magnetic materials.

3.1 Common mainline process: From spent NdFeB to high-purity rare-earth products (“the salt-solution platform” defines the separation window)

Stage	What you do (goal)	Where rare-earth salts “appear”	The most common difficulties at this step
① Pretreatment	Demagnetization, crushing/pulverization, sorting; handling coatings/binders, etc.	No salt formed yet, but it determines subsequent leaching behavior and impurity burden	Ni plating/coatings can affect acid choice and selective leaching
② Leaching	Bring rare earths from solids into solution (turn a “materials problem” into an “ion-separation problem”)	Forms a mixed rare-earth salt solution (commonly chloride/sulfate/nitrate media)	High acid consumption; extensive co-dissolution of iron; whether Ni plating dissolves; gaseous by-products plus safety and environmental burdens
③ Impurity removal / valence control	Preferentially remove major impurities such as Fe, or control their chemical forms	Rare earths remain in the salt solution; solution chemistry defines the impurity-removal window	Improper pH/redox conditions can cause co-precipitation or worsen selectivity in downstream separation
④ Separation & purification (core)	Split and purify Nd/Pr vs Dy/Tb and neighboring rare earths	Completed on the rare-earth salt solution platform (e.g., solvent extraction)	Rare-earth ions are highly similar; separation factors are small; typically relies on multi-stage cascades and tight control of the medium
⑤ Recovery as solid intermediates	“Catch” rare earths from solution as filterable solids for solid–liquid separation and downstream conversion	Produces precipitates such as oxalates / (sodium–rare-earth) double sulfates (e.g., NaRE(SO₄)₂). (Essentially still “rare-earth salt / rare-earth compound intermediates.”)	Precipitation selectivity and impurity entrainment; filtration/washing largely determine purity and reproducibility
⑥ Conversion to oxides / remanufacturing feedstock	Calcine to obtain REO (rare-earth oxides), then proceed to metal/alloy/magnet routes	“Salt/precipitated intermediate → oxide” is a common restart point	Impurity control and batch-to-batch consistency; downstream material performance is sensitive to this step

3.2 Three “gates” of the salt-solution platform: Why separation & purification becomes the bottleneck in rare-earth permanent-magnet recycling

Three gates	Why it determines success or failure	The role played by “rare-earth salts” here	What happens if it isn’t handled well
Gate 1: Choice of leaching medium (bring solids into solution)	This is the entry point that converts a “magnet materials problem” into an “ion-separation problem.” If the entry choice is wrong, every downstream step becomes harder and more expensive	Determines what kind of rare-earth salt solution forms (anion system, acidity, ionic strength) and how much impurities (Fe/Ni/Co, etc.) enter solution	Heavier impurity burden; more impurity-removal and separation stages; lower recovery and larger batch-to-batch fluctuations
Gate 2: Control of major-impurity chemical behavior (the impurity-removal window)	Permanent magnets require “element-level control + high purity,” but in solution, major impurities often dominate system behavior ahead of rare earths (especially Fe)	In the rare-earth salt solution, acidity, valence states, and complexation/hydration collectively determine whether rare earths co-precipitate/are entrained and whether the system stays stably separable	Not merely “impurities not removed cleanly”: it causes rare-earth loss, impurity carryover, and poorer separation selectivity—ultimately preventing purity and consistency from reaching spec
Gate 3: From mixed rare earths to element-level products (separation/purification stage count)	Rare-earth ions are highly similar; neighboring elements differ only slightly. Achieving magnet-grade purity often requires amplifying micro-differences through “selectivity × number of stages”	Separation occurs mainly on the rare-earth salt solution platform: the medium and anions affect true speciation and selectivity; flowsheet design determines whether stable compliance is achievable	Ultimately shows up as: cannot separate / cannot reach cleanliness / costs and stage count rise sharply; outputs cannot stably meet materials-side requirements over time

IV.Product Navigation Table | Rare-Earth Mainline: Quickly Locate Tables A–E by Research Task (Permanent Magnets—Separation/Purification—Recycling; with Controls/Extensions)

Need / Scenario	Which Table to Check First	Table-Selection Logic	Representative Products in the Table (Examples)
Rare-earth separation/purification methodology (solvent extraction, separation-factor evaluation, scale-up of stage numbers, precipitation recovery)	Table A: Key Additives and System Components for Separation/Purification	The key variables lie in “selectivity tools + system components”: extractants/co-extractants and precipitating agents directly determine whether adjacent rare earths can be pulled apart, and whether recovery is clean and readily filterable.	Oxalic acid dihydrate, HDEHP, P-507, bis(2,4,4-trimethylpentyl)phosphinic acid, TBP, ammonium cerium(IV) nitrate
Solution preparation, doping/precursor controls centered on “key rare earths for permanent magnets” (Nd/Pr/Dy/Tb related)	Table B: Key Rare Earths for Permanent Magnets—Salt Sources + Oxides	For the mainline task, first lock onto the target elements: Nd/Pr are the bulk constituents; Dy/Tb are often used for high-temperature demagnetization resistance and performance tuning. Table B consolidates these elements’ common salt sources + REO end-state forms, saving time and reducing the chance of missing key forms.	Nd₂O₃, NdCl₃·6H₂O, Nd(NO₃)₃·6H₂O; Pr₂Oₓ (praseodymium oxide), PrCl₃·7H₂O, Pr(NO₃)₃·6H₂O; Dy₂O₃, DyCl₃·6H₂O, Dy(NO₃)₃·xH₂O; Tb₄O₇, TbCl₃·6H₂O, Tb(NO₃)₃·6H₂O
Need a general rare-earth salt “aqueous solution platform” as universal salt sources for solution chemistry/coordination/complexation controls (not limited to permanent-magnet elements)	Table C: Salt-Solution Platform—Chlorides + Nitrates	If the task is system studies/controls in aqueous salt solutions (e.g., acidity, ionic strength, ligand effects, speciation comparison), prioritize chlorides/nitrates with high solubility and mature, well-characterized systems. Table C offers the broadest coverage for building general control systems.	LaCl₃·7H₂O, CeCl₃·7H₂O, SmCl₃·6H₂O, GdCl₃·6H₂O, YCl₃·6H₂O, ScCl₃·6H₂O; La(NO₃)₃·6H₂O, Ce(NO₃)₃·6H₂O, Gd(NO₃)₃·6H₂O, Y(NO₃)₃·6H₂O, etc.
Non-aqueous systems / Lewis-acid catalysis / precursor routes with controllable coordination environments (greater emphasis on anion effects and solvent compatibility)	Table D: Acetates + Triflates (OTf⁻)	When you want to avoid strongly coordinating halides, or need rare-earth (and rare-earth-like) Lewis-acid precursors better suited for non-aqueous systems, OTf⁻ and acetates are common entry points. Table D highlights that “anion/coordination environment dictates reactivity and solvent fit.”	Sc(OTf)₃, Yb(OTf)₃; lanthanum acetate / neodymium acetate / dysprosium acetate (hydrates)
“Recycling—calcination—final feedstock” workflows, or high-purity REO as a materials starting point/control (especially when impurity control and reproducibility matter)	Table E: Rare-Earth Oxide End-States / High-Purity Precursors	If the experiment ultimately requires REO (or uses REO as the formulation starting point), choose directly from Table E: it is the end-state form after “salt/precipitate intermediate → calcination,” and also the most common solid metal source on the materials side. High purity is more critical for batch-to-batch consistency and impurity troubleshooting.	La₂O₃, CeO₂, Y₂O₃, Sc₂O₃, Sm₂O₃, Eu₂O₃, Gd₂O₃, Ho₂O₃, Er₂O₃, Tm₂O₃, Yb₂O₃, Lu₂O₃

Table A | Key Additives and System Components for Separation/Purification (Precipitation / Extraction / Valence-State Control)

Category	CAS No.	Aladdin Cat. No.	Name	Specification / Purity	Product Positioning & Use (Mainline: Permanent Magnets—Separation/Purification—Recycling; incl. Controls/Extensions)
Rare-earth separation/recycling | Precipitant | Oxalate	6153-56-6	O433119	Oxalic acid dihydrate	Suitable for synthesis	A classic precipitant in hydrometallurgical rare-earth separation/recovery: precipitates Ln³⁺ in solution as oxalates for facile solid–liquid separation; calcination of the precipitate yields the corresponding rare-earth oxides (REOs), commonly used for recycling/regeneration and precursor preparation.
Rare-earth separation | Solvent extraction | Acidic phosphate extractant (HDEHP)	298-07-7	B399242	Di(2-ethylhexyl) phosphate (HDEHP)	≥99%	A benchmark acidic organophosphorus extractant for rare-earth separations: used in solvent-extraction separations and selectivity studies of metal ions; serves as a representative extractant illustrating how “selectivity × number of stages” can amplify small differences at the flowsheet level.
Rare-earth separation | Solvent extraction | Acidic phosphonic-acid extractant (P-507 / PC-88A type)	14802-03-0	M158251	(2-Ethylhexyl)phosphonic acid mono-2-ethylhexyl ester (P-507)	≥95% (T)	A commonly used acidic phosphonic-acid extractant for separating rare earths/nonferrous metals: improves separation selectivity and process efficiency; often used as a typical extractant control in rare-earth salt solution platforms (chloride/nitrate media).
Rare-earth separation | Solvent extraction | Phosphinic-acid extractant (Cyanex 272 type)	83411-71-6	D195222	Bis(2,4,4-trimethylpentyl)phosphinic acid	≥90%	A representative phosphinic-acid extractant: widely used for selective metal-ion separations and extraction-system studies; enables comparison of how different organophosphoric acids/phosphonic acids/phosphinic acids affect rare-earth separation selectivity.
Rare-earth separation | Solvent-extraction system | TBP (neutral extractant / modifier)	126-73-8	T431668	Tri-n-butyl phosphate (TBP)	European Pharmacopoeia (Ph.Eur.)	A classic neutral phosphate ester: more often used as an extractant/modifier component in specific nitrate systems and is valuable for controls; in rare-earth fine separations, the main workhorses are still typically acidic organophosphorus extractant systems.
Rare-earth related | Redox reagent | Ce(IV) salt (CAN)	16774-21-3	A485845	Ceric ammonium nitrate (IV)	European Pharmacopoeia (Ph.Eur.), suitable for analysis, ACS, superior grade	A representative Ce(IV) strong oxidant: primarily used in redox chemistry, analytical chemistry, and synthesis; also a classic reagent to illustrate the “cerium valence-state exception (Ce³⁺/Ce⁴⁺),” highlighting possible valence states and speciation differences of rare earths in solution.

Table B | Key Rare Earths for Permanent Magnets (Nd / Pr / Dy / Tb): Salt Sources + REO End-States

Category	CAS No.	Aladdin Cat. No.	Name	Specification / Purity	Product Positioning & Use (Mainline: Permanent Magnets—Separation/Purification—Recycling; incl. Controls/Extensions)
Rare-earth oxide | REO end-state/precursor | Neodymium oxide	1313-97-9	N105307	Neodymium oxide	PrimorTrace™, ≥99.99% metals basis	One of the key rare earths in the permanent-magnet mainline: Nd₂O₃ is an important form for regeneration/production of neodymium salts and materials precursors; higher purity is more favorable for downstream “element-level control and batch-to-batch consistency.”
Rare-earth salt | Chloride | Hexahydrate	13477-89-9	N123721	Neodymium(III) chloride hexahydrate	≥99.9% metals basis	Permanent-magnet key element Nd: a high-purity Nd³⁺ chloride salt source (chloride medium) for rare-earth salt solution platforms, coordination/complexation controls, and materials precursors; suitable for impurity-sensitive systems and reproducibility validation.
Rare-earth salt | Nitrate | Hexahydrate nitrate	16454-60-7	N106057	Neodymium nitrate hexahydrate	AR, ≥99%	Permanent-magnet key element Nd: a commonly used Nd³⁺ nitrate salt source for solution preparation, materials precursors, and separation/extraction-system controls; AR grade is suitable as a general salt source and a starting point for process validation.
Rare-earth oxide | REO end-state/precursor | Praseodymium oxide	12037-29-5	P128241	Praseodymium oxide	PrimorTrace™, ≥99.99% metals basis	One of the key light rare earths (Pr) in the permanent-magnet mainline: used as a Pr source for praseodymium salts/precursors and functional oxides; corresponds to a common REO form and a high-purity control within the “separation/purification—regenerated feedstock” chain.
Rare-earth salt | Chloride | Heptahydrate	10025-90-8	P302025	Praseodymium chloride heptahydrate	≥99%	Permanent-magnet key light rare earth Pr: a commonly used salt source in chloride media for preparing salt solutions, precursors, and separation/complexation controls; together with Pr(NO₃)₃ and Pr oxides, forms a complete “form chain.”
Rare-earth salt | Nitrate | Hexahydrate nitrate	15878-77-0	P106056	Praseodymium(III) nitrate hexahydrate	PrimorTrace™, ≥99.99% metals basis	Permanent-magnet key light rare earth Pr: a high-purity Pr³⁺ nitrate precursor, commonly used in solution synthesis and separation/complexation systems.
Rare-earth oxide | REO end-state/precursor | Dysprosium oxide	1308-87-8	D105275	Dysprosium oxide	PrimorTrace™, ≥99.99% metals basis	One of the key heavy rare earths in the permanent-magnet mainline: Dy₂O₃ is widely used to prepare dysprosium salts/doping systems and materials precursors; high purity aids impurity troubleshooting and consistency controls in high-temperature anti-demagnetization studies.
Rare-earth salt | Chloride | Hexahydrate	15059-52-6	D189029	Dysprosium chloride hexahydrate	PrimorTrace™, ≥99.99% metals basis	Permanent-magnet key heavy rare earth Dy: a high-purity Dy³⁺ chloride salt source (chloride medium) for rare-earth salt solutions, separation/complexation behavior studies, and materials precursors; suitable for impurity-sensitive controls in high-temperature anti-demagnetization systems.
Rare-earth salt | Nitrate | Hydrated nitrate	100641-13-2	D475065	Dysprosium(III) nitrate hydrate	≥99.9% metals basis	Permanent-magnet key heavy rare earth Dy: a nitrate-medium salt source, suitable for studying medium differences versus DyCl₃; also usable as a control relevant to “nitrate feed” conditions in solvent-extraction/complexation systems.
Rare-earth oxide | REO end-state/precursor | Terbium oxide	12037-01-3	T105880	Terbium oxide	PrimorTrace™, ≥99.999% metals basis	High-purity Tb oxide: commonly used for terbium salts / Tb-doped materials precursors; in permanent magnets and high-purity rare-earth contexts, Tb is one of the key heavy rare earths (high purity benefits consistency and impurity troubleshooting).
Rare-earth salt | Chloride | Hexahydrate	13798-24-8	T100635	Terbium chloride hexahydrate	PrimorTrace™, ≥99.999% metals basis	High-purity Tb³⁺ salt source: used for luminescent/magneto-optical/functional-oxide precursor systems and solution-chemistry studies; also serves as a control for coordination/complexation differences within rare-earth salt systems.
Rare-earth salt | Nitrate | Hexahydrate nitrate	13451-19-9	T475227	Terbium(III) nitrate hexahydrate	PrimorTrace™, ≥99.999% metals basis	High-purity Tb³⁺ nitrate: used for Tb doping, luminescent-material precursors, and solution-chemistry controls; suitable for experiments requiring stringent trace-metal control and batch-to-batch consistency.

Table C | Rare-Earth Salt Solution Platform: Chlorides + Nitrates (Common Salt Sources for Separation/Purification and Controls)

Category	CAS No.	Aladdin Cat. No.	Name	Specification / Purity	Product Positioning & Use (Mainline: Permanent Magnets—Separation/Purification—Recycling; incl. Controls/Extensions)
Rare-earth salt | Chloride | Heptahydrate	10025-84-0	L431126	Lanthanum chloride heptahydrate	PrimorTrace™, ≥99.999% metals basis	Typical light rare earth La³⁺ salt source: commonly used in rare-earth salt solution platforms (chloride medium), coordination chemistry, and materials precursors; high purity supports reproducibility in separation/doping studies.
Rare-earth salt | Chloride | Heptahydrate	18618-55-8	C432245	Cerium(III) chloride heptahydrate	purum p.a., ≥98% (AT)	Common Ce³⁺ chloride salt source: used in solution chemistry/coordination and materials precursor systems; also serves as a typical salt in rare-earth solution platforms (chloride medium) for separation/complexation behavior controls.
Rare-earth salt | Chloride | Hexahydrate	13465-55-9	S140022	Samarium chloride hexahydrate	PrimorTrace™, ≥99.99% metals basis	High-purity Sm³⁺ chloride salt source: a representative of the rare-earth salt solution platform (chloride medium) for solution preparation, coordination/complexation controls, and materials precursors; high purity helps control trace impurities and batch consistency.
Rare-earth salt | Chloride | Hexahydrate	13759-92-7	E119161	Europium(III) chloride hexahydrate	PrimorTrace™, ≥99.99% metals basis	High-purity Eu³⁺ salt source: used for luminescent materials/coordination-chemistry precursors and solution controls.
Rare-earth salt | Chloride | Hexahydrate	13450-84-5	G119153	Gadolinium(III) chloride hexahydrate	≥99.9% metals basis	Gd³⁺ chloride salt source: used for magnetic/functional-oxide precursors and solution-chemistry studies; as a chloride-medium representative, it can serve in separation/complexation behavior controls.
Rare-earth salt | Chloride | Hexahydrate	14914-84-2	H119101	Holmium(III) chloride hexahydrate	≥99.9% metals basis	Ho³⁺ chloride salt source: a heavy rare-earth salt source for optical/magneto-optical materials precursors and solution-chemistry controls; also usable as a heavy-rare-earth control system in separation/purification studies.
Rare-earth salt | Chloride | Hexahydrate	10025-75-9	E119092	Erbium(III) chloride hexahydrate	≥99.995% metals basis	High-purity Er³⁺ chloride salt source: commonly used for optical/laser-related doped-material precursors and solution-chemistry controls; high purity suits trace-impurity-sensitive systems.
Rare-earth salt | Chloride | Hexahydrate	1331-74-4	T119077	Thulium(III) chloride hexahydrate	PrimorTrace™, ≥99.99% metals basis	High-purity Tm³⁺ chloride: a heavy rare-earth salt source for solution chemistry and doped-material precursors; as a chloride-medium representative, it is useful for comparing anion effects on solubility and speciation.
Rare-earth salt | Chloride | Hexahydrate	10035-01-5	Y196893	Ytterbium(III) chloride hexahydrate	PrimorTrace™, ≥99.99% metals basis	High-purity Yb³⁺ chloride: a commonly used heavy rare-earth salt source for solution chemistry, non-aqueous controls, and functional-material precursors; high purity helps minimize trace-metal interference.
Rare-earth salt | Chloride | Hexahydrate	15230-79-2	L119054	Lutetium(III) chloride hexahydrate	PrimorTrace™, ≥99.99% metals basis	High-purity Lu³⁺ chloride salt source: used for heavy rare-earth salt solutions and coordination/complexation controls; also a typical salt source for heavy rare earths in separation flowsheets and materials doping.
Rare-earth salt | Chloride | Hexahydrate	10025-94-2	Y119237	Yttrium(III) chloride hexahydrate	PrimorTrace™, ≥99.999% metals basis	High-purity Y³⁺ salt source: highly water-soluble; commonly used to prepare Y-based materials (e.g., oxides/phosphor precursors) and for solution-chemistry studies; also serves as a control salt in rare-earth solution platforms.
Rare-earth salt | Chloride | Hexahydrate	20662-14-0	S475229	Scandium(III) chloride hexahydrate	PrimorTrace™, ≥99.999% metals basis	High-purity Sc³⁺ salt source: used to prepare scandium salt solutions and Sc-doped systems; suitable for impurity-sensitive materials precursors and controls in catalysis/inorganic synthesis.
Rare-earth salt | Nitrate | Hexahydrate nitrate	10277-43-7	L106051	Lanthanum nitrate hexahydrate	PrimorTrace™, ≥99.999% metals basis	High-purity La³⁺ nitrate: commonly used as a lanthanum source for solution synthesis/sol–gel routes; as a nitrate-medium representative, it can serve in extraction/complexation controls and materials precursor preparation.
Rare-earth salt | Nitrate | Hexahydrate nitrate	10294-41-4	C431281	Cerium(III) nitrate hexahydrate	Ultrapure grade	A water-soluble Ce³⁺ metal source: commonly used to prepare rare-earth salt solutions, materials synthesis (e.g., catalysts/inorganic functional-material precursors), and separation-system studies; ultrapure grade supports trace-impurity control and reproducibility controls.
Rare-earth salt | Nitrate | Hexahydrate nitrate	13759-83-6	S109297	Samarium(III) nitrate hexahydrate	PrimorTrace™, ≥99.99% metals basis	High-purity Sm³⁺ nitrate: good water solubility; suitable for nitrate-medium separation/complexation controls and materials precursor preparation; used to compare chloride vs nitrate media in terms of speciation and process windows.
Rare-earth salt | Nitrate | Hexahydrate nitrate	19598-90-4	G106606	Gadolinium nitrate hexahydrate	PrimorTrace™, ≥99.999% metals basis	High-purity Gd³⁺ nitrate: good water solubility; commonly used as a precursor for Gd-based materials/magnetic systems and for solution-chemistry studies; nitrate media are also frequently used for solvent-extraction/complexation controls.
Rare-earth salt | Nitrate | Hexahydrate nitrate	13494-98-9	Y118878	Yttrium nitrate hexahydrate	PrimorTrace™, ≥99.99% metals basis	High-purity Y³⁺ nitrate: a typical nitrate-medium representative, commonly used for solution synthesis/sol–gel routes and extraction/complexation controls; also used to prepare Y-based oxides/phosphor precursors, etc.

Table D | Extension of Anions/Coordination Environments: Acetates + Triflates (OTf⁻) (Non-aqueous / Coordination Control)

Category	CAS No.	Aladdin Cat. No.	Name	Specification / Purity	Product Positioning & Use (Mainline: Permanent Magnets—Separation/Purification—Recycling; incl. Controls/Extensions)
Rare-earth salt | Carboxylate | Acetate	100587-90-4	L118478	Lanthanum acetate hydrate	PrimorTrace™, ≥99.99% metals basis	A common La³⁺ organic-acid salt precursor: suitable for sol–gel routes, coordination control, organic–inorganic hybrids, and related materials syntheses; can be used to compare “anion/coordination environment” differences versus chlorides/nitrates.
Rare-earth salt | Carboxylate | Acetate	334869-71-5	N106127	Neodymium(III) acetate hydrate	≥99.9% metals basis	An Nd³⁺ acetate precursor: commonly used in sol–gel and coordination-control routes as an organic-acid form of the key permanent-magnet element Nd; can be compared with NdCl₃ and Nd(NO₃)₃ to probe anion effects.
Rare-earth salt | Carboxylate | Acetate	15280-55-4	D189031	Dysprosium acetate hydrate	≥99.9% metals basis (REO)	A Dy³⁺ acetate precursor: suitable for sol–gel routes, coordination control, and organic–inorganic systems; comparison with DyCl₃ and Dy(NO₃)₃ highlights how “anion/coordination environment” impacts dissolution and reactivity.
Rare-earth salt | Organic coordination salt | Triflate (OTf⁻)	144026-79-9	S475205	Scandium(III) trifluoromethanesulfonate	≥99.995% metals basis	A typical Sc(OTf)₃ Lewis-acid precursor: widely used in organic synthesis/catalysis and non-aqueous systems; a representative of “anion design (OTf⁻) for rare-earth/rare-earth-like salts,” illustrating how different anions affect reactivity and solvent compatibility.
Rare-earth salt | Organic coordination salt | Triflate (OTf⁻)	54761-04-5	Y475150	Ytterbium(III) trifluoromethanesulfonate	PrimorTrace™, ≥99.99% metals basis	A typical rare-earth Lewis-acid precursor: commonly used in organic synthesis/catalysis and non-aqueous systems; also a representative showing rare-earth salts are not limited to halides/nitrates, enabling comparisons of how anions affect solubility/coordination and reactivity.

Table E | Rare-Earth Oxides (REOs): End-States and High-Purity Precursors (Covering the “Salt → Precipitation/Calcination → REO” Endpoint)

Category	CAS No.	Aladdin Cat. No.	Name	Specification / Purity	Product Positioning & Use (Mainline: Permanent Magnets—Separation/Purification—Recycling; incl. Controls/Extensions)
Rare-earth oxide | REO end-state/precursor | Lanthanum oxide	1312-81-8	L431805	Lanthanum(III) oxide	Basic-grade reagent, for preparation	A common light rare-earth oxide precursor: used to prepare lanthanum salts (chlorides/nitrates/acetates, etc.) and La-based oxide materials; often serves as an REO end-state or a reprocessing feedstock starting point in rare-earth separation and recycling.
Rare-earth oxide | Nano-oxide | CeO₂	1306-38-3	C431729	Cerium(IV) oxide	Nanopowder, particle size <25 nm (BET)	A representative nano rare-earth oxide: widely used in catalysis/polishing/oxygen-storage–release related materials; corresponds to an end-state in the “salt → precipitation/calcination → oxide” chain, and can also serve as a cerium-source control for downstream salt making/doping systems.
Rare-earth oxide | REO end-state/precursor | Yttrium oxide	1314-36-9	Y431838	Yttrium oxide 99+	Suitable for analysis, superior grade, ≥99%	A typical REO end-state/precursor: commonly used as a Y source for preparing various yttrium salts (e.g., chlorides/nitrates) and functional materials (ceramics/optics/luminescence, etc.); also used for purity/impurity-control benchmarking.
Rare-earth oxide | REO end-state/precursor | Scandium oxide	12060-08-1	S110936	Scandium(III) oxide	PrimorTrace™, ≥99.999% metals basis	High-purity Sc₂O₃: used to prepare scandium salts and Sc-doped oxides/functional ceramics; a common high-purity metal source and control precursor within rare-earth/rare-earth-like element systems.
Rare-earth oxide | REO end-state/precursor | Samarium oxide	12060-58-1	S118883	Samarium oxide	PrimorTrace™, ≥99.999% metals basis	High-purity REO: suitable for materials/magnetic and optical control experiments requiring strict impurity control; also commonly used as a starting material for samarium salts and Sm-doped systems.
Rare-earth oxide | REO end-state/precursor | Europium oxide	1308-96-9	E106508	Europium oxide	PrimorTrace™, ≥99.99% metals basis	High-purity Eu₂O₃: one of the commonly used precursors in luminescent-material systems.
Rare-earth oxide | REO end-state/precursor | Gadolinium oxide	12064-62-9	G105875	Gadolinium oxide	PrimorTrace™, ≥99.99% metals basis	High-purity Gd₂O₃: used to prepare gadolinium salts and magnetic/functional-oxide precursors; corresponds to a common REO end-state in separation/recycling and is convenient for impurity-control benchmarking.
Rare-earth oxide | REO end-state/precursor | Holmium oxide	12055-62-8	H105899	Holmium oxide	PrimorTrace™, ≥99.99% metals basis	High-purity Ho₂O₃: commonly used as a precursor for optical/magneto-optical and functional materials; as a heavy-rare-earth oxide control, it can also be used for salt making and doping studies.
Rare-earth oxide | REO end-state/precursor | Erbium oxide	12061-16-4	E105903	Erbium oxide	PrimorTrace™, ≥99.99% metals basis	High-purity Er₂O₃: commonly used for optical/laser-related material precursors and doping controls; also serves as a starting point for preparing erbium salts.
Rare-earth oxide | REO end-state/precursor | Thulium oxide	12036-44-1	T105902	Thulium oxide	≥99.99% (REO)	Tm₂O₃: a heavy rare-earth oxide end-state/precursor used to prepare thulium salts and dope functional materials; serves as an REO-form control within the “salt → oxide” conversion chain.
Rare-earth oxide | REO end-state/precursor | Ytterbium oxide	1314-37-0	Y118477	Ytterbium oxide	PrimorTrace™, ≥99.99% metals basis	High-purity Yb₂O₃: a heavy rare-earth oxide precursor commonly used to prepare ytterbium salts and dope functional materials (optics/catalysis, etc.).
Rare-earth oxide | REO end-state/precursor | Lutetium oxide	12032-20-1	L105574	Lutetium oxide	PrimorTrace™, ≥99.99% metals basis	High-purity Lu₂O₃: a typical heavy rare-earth oxide precursor/end-state used to prepare lutetium salts (chlorides/nitrates, etc.) and heavy-rare-earth-doped functional materials; suitable for controls and reproducibility studies in trace-metal-sensitive systems.

Note: The above are representative Aladdin products. For more specifications, please refer to the product list at the end of the article, or search the Aladdin website using the “product name / CAS / catalog number.”

Aladdin: https://www.aladdinsci.com/

For more related articles, please see below:

Post-Transition Metals and Their Salts: A Classification Guide from Definitions to Value-Chain Applications (Including Product Lists in Tables 1–4)

What Are Rare Earths? Material Logic of 17 Elements, an Application Map, and a Quick Guide to Aladdin Reagent Selection (Oxides/Salts/Metals/Standard Solutions/Dispersions)

Rare Earth Oxides Primer: From RE₂O₃ to “Oxygen-Storage” Oxides (Ce/Pr/Tb)—Material Logic, Classification Guide, and a 3-Step Selection Workflow