Materials new or newly commercial since the first edition, plus research-stage materials worth tracking, in evaluation order.
Cs2HfCl6 (CHC): most consequential new scintillator since GAGG:Ce. Characterized mid-2010s [1]; commercial sizes since 2022.
Properties. Density 3.86 g/cc, cubic (K2PtCl6 type), melting point about 820 C, non-hygroscopic (plastic/epoxy packaging). Emission about 400 nm (bialkali PMT / NUV SiPM match). Decay about 4 us (limits high-rate use). Light yield to 54,000 photons/MeV (small crystals), about 23,000 in one-inch boules [2]. Resolution at 662 keV: 2.8 % (15 mm [3]), 3.5 % (one-inch [2]), 3.3 % (first spectrometers [1]). Non-proportionality rivals LaBr3:Ce.
Status. Commercial to about 30 mm cubed, several months' lead time. Best fit: handheld isotope ID, low-background spectrometry, ruggedized field units. Poor fit: high-rate counting, large volume, fast timing.
Single-doped GAGG:Ce decay: 90 to 150 ns with a slow component. Mg co-doping (GAGG:Ce,Mg) cuts this to 50 to 90 ns, modest yield loss [4]; now preferred for high-rate/timing use. Ca co-doping raises yield but slows decay further; B co-doping also studied.
Compositional substitution in the garnet host changes scintillation properties without altering the activator [5]:
GYAGG:Ce: density 5.8 g/cc, yield 110 to 130 % of NaI(Tl). Y-for-Gd substitution cuts self-absorption, enabling larger crystals.
LuAG:Ce: density 6.73 g/cc, yield 50 to 60 % of NaI(Tl). Used where stopping power beats yield (fast-timing PET).
LuAG:Pr: decay about 20 ns, fastest garnet; emission at 305 nm needs a UV-transmissive window or NUV-sensitive SiPM.
Transparent ceramic garnets (LuAG:Ce, GAGG:Ce, GYAGG:Ce, YAG:Ce): powder-sintered, not Czochralski-grown, enabling complex shapes and shorter lead times. Resolution 5 to 7 % at 662 keV, below best single crystals; driven by PET-array and radiography-panel demand.
CsI(Tl) is not new (since the 1950s); the new story is SiPM-optimized readout. Emission at 550 nm matches SiPM PDE (about 55 %) far better than bialkali PMT QE (about 12 %), a 4 to 5 fold gain; yield 165 % of NaI(Tl) (silicon-matched); robust and only modestly hygroscopic.
Optimized CsI(Tl)+SiPM: 6 to 7 % FWHM at 662 keV (1-inch cube), matching NaI(Tl)+PMT; NaI(Tl)+PMT regains the cost edge at 3-inch and up.
SrI2(Eu): commercial to about 40 mm cubed. Resolution 2.5 to 2.7 % FWHM at 662 keV (best samples), rivaling LaBr3:Ce. Decay 1 to 5 us limits rate; hygroscopicity severe, hermetic packaging required.
Vs. LaBr3:Ce: no intrinsic background, sometimes cheaper, slightly better low-energy non-proportionality; but slower, and LBC/thin-shielding variants are narrowing LaBr3:Ce's La-138 disadvantage. Remains a low-background spectrometry niche rather than a broad replacement.
Elpasolites (CLYC, CLLB, CLLBC): now standard catalog items in homeland-security and physics applications.
CLYC (Cs2LiYCl6:Ce): 3.31 g/cc, decay 1/50/1000 ns, yield 30 to 40 % of NaI(Tl), resolution 5 to 6 % at 662 keV, PSD FoM 2.5 to 3.5, hygroscopic.
CLLB / CLLBC (Cs2LiLaBr6:Ce / Cs2LiLa(Br,Cl)6:Ce): about 4.1 g/cc, yield 60 to 70 % of NaI(Tl), PSD FoM above 3, resolution 4 to 5 % (CLLBC); has displaced CLYC in new handheld designs.
Commercial to 1.5-inch cubed routine; 3-inch cubed available in CLLBC with longer lead times. Future gains likely incremental (PSD, cost, size).
Perovskites (CsPbBr3, CsPbCl3, CsPbI3, lead-free Cs2AgInCl6): researched since about 2015 for high yield (above 200 % of NaI(Tl)), sub-ns decay, solution-processed growth. None commercial yet: moisture/light instability, poor reproducibility at useful sizes, lead toxicity. Best prospect: sub-millimeter-pixel X-ray imaging panels [6].
Nanocomposites embed inorganic nanoparticles (quantum dots, oxide/halide particles) in polymer or glass to combine inorganic stopping power with organic cost/formability; light extraction at the particle-matrix interface is the main obstacle. QD variants (CdSe/ZnS, InP/ZnS, perovskite QDs) tune emission via confinement. Research-stage only (proof-of-concept detectors, no commercial product); best fit would be large-area, cost-sensitive gamma-imaging panels.
Table A.1 - State of new and emerging scintillators (2026)
| Material | Stage | Best resolution at 662 keV | Decay | Hygroscopic | Likely 2030 status |
|---|---|---|---|---|---|
| Cs2HfCl6 (CHC) | Commercial scaling | 2.8 % best published [3]; 3.5 % in one-inch boules [2] | 4 us | No | Standard catalog |
| GAGG:Ce,Mg | Commercial mature | 5-6 % | 50-90 ns | No | Standard catalog |
| GYAGG:Ce | Commercial mature | 5-6 % | 60-90 ns | No | Standard catalog |
| LuAG:Pr | Commercial niche | 8-10 % | 20 ns | No | Standard for fast-timing |
| Transparent ceramic garnets | Commercial scaling | 5-7 % | varies | No | Standard for arrays |
| Optimized CsI(Tl)+SiPM | Commercial mature | 6-7 % | 0.6/3.4 us | Slightly | Dominant handheld config |
| SrI2(Eu) | Commercial mature | 2.5-2.7 % | 1-5 us | Yes | Niche standard |
| CLLBC | Commercial mature | 4-5 % | 55/270/1100 ns | Yes | Standard for n+gamma |
| Perovskites (CsPbX3) | Research | 8-12 % | sub-ns to ns | varies | Niche imaging only |
| Quantum-dot composites | Research | n/a (low resolution) | varies | depends | Specialized only |
Take-away: the commercially meaningful materials are Cs2HfCl6, the codoped and substituted garnets, optimized CsI(Tl)+SiPM, and CLLBC; the rest remains research. Design in substitution flexibility (for example a LaBr3:Ce fallback for CHC) as a procurement hedge.
[1] A. Burger et al., "Cesium hafnium chloride: A high light yield, non-hygroscopic cubic crystal scintillator for gamma spectroscopy," Appl. Phys. Lett., vol. 107, art. 143505, 2015.
[2] R. Hawrami et al., "Advanced high-performance large diameter Cs2HfCl6 (CHC) and mixed halides scintillator," J. Cryst. Growth, vol. 533, art. 125473, 2020.
[3] E. Ariesanti, R. Hawrami, A. Burger, and S. Motakef, "Improved growth and scintillation properties of intrinsic, non-hygroscopic scintillator Cs2HfCl6," J. Lumin., vol. 217, art. 116784, 2020.
[4] M. T. Lucchini et al., "Effect of Mg2+ ions co-doping on timing performance and radiation tolerance of Cerium doped Gd3Al2Ga3O12 crystals," Nucl. Instrum. Methods A, vol. 816, pp. 176-183, 2016.
[5] M. Nikl and A. Yoshikawa, "Recent R&D trends in inorganic single-crystal scintillator materials for radiation detection," Adv. Opt. Mater., vol. 3, pp. 463-481, 2015.
[6] Q. Chen et al., "All-inorganic perovskite nanocrystal scintillators," Nature, vol. 561, pp. 88-93, 2018.