Progress in Preparation and Mechanical Properties of Single-Crystal Fiber Materials

doi:10.16553/j.cnki.issn1000-985x.2026.0080

Abstract

Abstract: Single-crystal fiber materials combine the inherent advantages of single-crystal materials in terms of optical， scintillation， and multifunctional properties with the structural benefits of fiber configurations in miniaturization， flexible transmission， and device integration. They hold broad application prospects in fields of radiation detection， laser technology， and optoelectronic devices. In recent years， with the advancement of crystal growth technology， researches on the preparation methods and performance control of single-crystal fiber materials have being continuously deepened. This paper focuses on the research progress in the preparation and mechanical properties of single-crystal fiber materials. It systematically reviews the characteristics， scope of application， and current status of major fabrication processes， such as the laser-heated pedestal growth method， micro-pulling-down method， and Czochralski method. It also outlines the primary material systems for single-crystal fibers and， by using sapphire single-crystal optical fibers as an example， introduces their mechanical properties and defect mechanisms. Overall， the mechanical properties of single-crystal fibers are jointly determined by the intrinsic properties of the material and the preparation process， with defect control and stress regulation being the key to enhancing structural integrity and operational reliability. Future research should focus on controllable fabrication of high-quality， characterization of multiscale mechanical properties， and investigation of multi-field coupled service behavior to advance the development of single-crystal fibers toward high-performance and engineering applications.

Key words: single-crystal fiber; laser-heated pedestal growth method; micro-pulling-down method; mechanical property; defect mechanism

CLC Number:

TB383

ZHENG Chuchu, YU Jinshan, WANG Honglei, ZHOU Xingui, GOU Yanzi. Progress in Preparation and Mechanical Properties of Single-Crystal Fiber Materials[J]. Journal of Synthetic Crystals, 2026, 55(7): 1005-1021.

Figures/Tables 21

Fig.1 Comparison of sapphire crystal fiber with diameter of 60 μm with human hair［5］

Fig.2 Photos of Yb∶YAP single-crystal fibers［17］

Fig.3 Surface characterization images and SEM images of barium fluoride single-crystals［22］

Fig.4 （a） LHPG system diagram；（b） sapphire tube with a fused quartz capillary［25］

Fig.5 Schematic diagram of the growth process of the single-crystal fiber［26］

Fig.6 Schematic diagram of a micro-pull-down device［35］

Fig.7 Diagram of an Inductive CZ crystal growth system［12］

Fig.8 Schematic diagram of the EFG original unit［42］

Fig.9 Diagram of axial stress distribution for sapphire single-crystal fibers in two directions［5］

Fig.10 Anisotropy of average axial phase difference of sapphire single-crystal fiber［5］

Fig.11 Diagram of radial stress distribution for sapphire single-crystal fibers in two directions［5］

Fig.12 Anisotropy of average radial phase difference of sapphire single-crystal fibers［5］

Fig.13 Comparison of high-temperature stress-strain curves and tensile strength for 100 μm sapphire fibers with different orientations［47］

Fig.14 Comparison of the room-temperature tensile strengths of sapphire fibers with different diameters［47］

Table 1 Tensile strength of sapphire single-crystal fibers with different diameters［5］

Sample	Diameter/μm	Tensile strength/MPa
Sapphire single-crystal fiber-1	50	3 396
Sapphire single-crystal fiber-2	60	3 696
Sapphire single-crystal fiber-3	100	3 012

Table 2 Tensile strength of sapphire single-crystal fibers annealed at different temperatures［5］

Sample	Temperature/℃	Tensile strength/MPa
Sapphire single-crystal fiber	—	4 166
Sapphire single-crystal fiber-400	400	3 323
Sapphire single-crystal fiber-800	800	2 757
Sapphire single-crystal fiber-1 600	1 600	2 464

Fig.15 Images of fiber surface morphology annealed at different temperatures［5］

Fig.16 （a） Cross-sectional morphology of unannealed fibers；（b） cross-sectional morphology of fibers annealed at 1 600 ℃［5］

Fig.17 Comparison of the creep of sodium-free YAG fibres， prefired to 1 400 and 1 550 °C/3 h， over the temperature range from1 000 ℃ to 1 350 ℃， and previously reported polycrystalline YAG fibers manufactured by the authors from the same process［53］

Table 3 Mechanical property comparison of single-crystal fibers in different material systems［17，53，58，59］

材料体系	代表材料	弹性模量/GPa	抗拉/抗弯强度/MPa	主要力学短板	应用场景
氧化物单晶	蓝宝石	340~470（与取向相关）	3 000~8 000（细径）	解理脆性、热应力敏感	高温传感、红外窗口
氧化物单晶	YAG	280~320	236（4点弯曲）	加工损伤敏感	激光增益介质、结构复合
氟化物单晶	CaF₂	76~146（与取向相关）	50~100	低硬度、热震脆性	红外光学、窗口
钙钛矿单晶	YAP	280~320	—	相变、各向异性热膨胀	非线性光学、调制器

Table 4 Comparison of influences of various preparation methods on mechanical properties of single-crystal fibers

制备技术	工艺特点	典型缺陷与结构特征	对力学性能的主要影响	适用材料体系
LHPG	无坩埚、局域加热、温度梯度大	位错密度较高，表面微裂纹，直径波动（熔区不稳定），直径可极细	无污染，本征强度高，但热应力大，蠕变抗力低，直径均匀性难控	高熔点氧化物、激光晶体
μ-PD	坩埚供料、连续生长、温度梯度中等	坩埚材料污染，成分偏析，表面缺陷，晶粒较大	长度长、直径均匀，适合规模化，但杂质降低高温蠕变抗力，晶界弱化	氧化物、激光晶体、闪烁晶体
CZ	大熔体、慢速生长、温度梯度小	位错密度低，热应力小，直径大（无法直接成纤）	晶体完整性好，缺陷少，本征力学性能高，但无法直接生长细径纤维，需后加工（引入机械损伤）	大尺寸单晶
EFG	模具约束截面、毛细供料、连续成形	模具污染，表面有划痕（脱模），有残余应力（各向异性热膨胀），截面规则（矩形/六角）	截面形状可控，适合异形纤维，但表面损伤降低强度，模具寿命短	规则截面纤维

References 59

[1]	LEBBOU K， BOULON G. Oxide fiber crystals grown by μ-PD and LHPG techniques［M］// Fiber Crystal Growth from the Melt. Berlin， Heidelberg： Springer， 2004： 219-254.
[2]	YANG Y L， YE L H， BAO R J， et al. Growth and characterization of Yb∶Ho∶YAG single crystal fiber［J］. Infrared Physics & Technology， 2018， 91： 85-89.
[3]	ZHANG Y B. Single-crystal sapphire-based optical high-temperature sensor for harsh environments［J］. Optical Engineering， 2004， 43（1）： 157. DOI URL
[4]	顾　鹏，王鹏刚，官伟明，等. 单晶光纤生长技术研究进展［J］. 人工晶体学报， 2021， 50（12）： 2362-2378.
	GU P， WANG P G， GUAN W M， et al. Research progress on growth techniques of single crystal fiber［J］. Journal of Synthetic Crystals， 2021， 50（12）： 2362-2378 （in Chinese）.
[5]	张泽宇，吴宇飞，王　涛，等. 蓝宝石单晶光纤生长及性能研究［J］. 人工晶体学报， 2023， 52（7）： 1335-1344.
	ZHANG Z Y， WU Y F， WANG T， et al. Growth and property of sapphire single crystal fibers［J］. Journal of Synthetic Crystals， 2023， 52（7）： 1335-1344 （in Chinese）.
[6]	LIU B， BURIC M P， YU Z H， et al. Attenuation measurements in single-crystal sapphire fiber via Raman scattering intensity［C］// Optical Components and Materials XV. January 27-February 1， 2018. San Francisco， USA. SPIE， 2018： 30.
[7]	XU Y， PENG Z G， SHI Y H， et al. Compact 80 W， 1 MHz femtosecond chirped pulse amplification laser system based on a Yb-doped fiber and a Yb∶YAG thin rod［J］. IEEE Photonics Journal， 2022， 14（2）： 1518506.
[8]	倪　勇. 基于Yb∶YAG单晶光纤的百瓦、毫焦量级飞秒激光啁啾脉冲放大系统研究［D］. 深圳：深圳大学， 2023.
	NI Y. Research on chirped pulse amplification system of hundred watt and millijoule femtosecond laser based on Yb∶YAG single crystal fiber［D］. Shenzhen： Shenzhen University， 2023 （in Chinese）.
[9]	XU X， LEBBOU K， MORETTI F， et al. Ce-doped Lu∶AG single-crystal fibers grown from the melt for high-energy physics［J］. Acta Materialia， 2014， 67： 232-238. DOI URL
[10]	ANDREETA M R B， ANDREETA E R M， HERNANDES A C， et al. Thermal gradient control at the solid-liquid interface in the laser-heated pedestal growth technique［J］. Journal of Crystal Growth， 2002， 234（4）： 759-761. DOI URL
[11]	LIU B， OHODNICKI P R. Fabrication and application of single crystal fiber： review and prospective［J］. Advanced Materials Technologies， 2021， 6（9）： 2100125. DOI URL
[12]	HADIDCHI S， TAVAKOLI M H. Optimization of argon gas flow rate for high-quality germanium crystal growth in Czochralski method［J］. Heat Transfer， 2025， 54（4）： 2632-2644. DOI URL
[13]	CHEN H， BURIC M， OHODNICKI P R， et al. Review and perspective： sapphire optical fiber cladding development for harsh environment sensing［J］. Applied Physics Reviews， 2018， 5： 011102.
[14]	YU Y， BHOWMIK K K， LI R， et al. In situ growth of halide perovskite crystals and thin films on optical fiber end facets［J］. RSC Advances， 2026， 16（5）： 3995-4003. DOI URL
[15]	PENG Q P， HE Z L， CHEN J H， et al. Organic-inorganic metal halide glass optical fibers for ultralow-loss and bendable photonic applications［J］. Matter， 2025， 8（11）： 102277. DOI URL
[16]	LEONOV S， BAH S T， BERNIER M， et al. FBG-assisted Q-switched Er-doped fluoride fiber laser using a saturable absorber in transmission［J］. Optics & Laser Technology， 2026， 194： 114305.
[17]	汪晨，张家玮，张华利，等. Yb∶YAP单晶光纤的生长及光谱性能研究［J］. 人工晶体学报， 2026， 55（1）： 46-51. DOI
	WANG C， ZHANG J W， ZHANG H L， et al. Growth and spectral properties of Yb∶YAP single crystal fiber［J］. Journal of Synthetic Crystals， 2026， 55（1）： 46-51 （in Chinese）. DOI
[18]	WANG L F， WANG Y N， LI X， et al. Precision-controlled laser slicing mechanism of isotropic lutetium oxide single crystals［J］. Materials Science and Engineering： B， 2026， 328： 119318.
[19]	CHU H W， QIAO W C， WANG X M， et al. Powerful ultrafast hybrid PM Yb∶fiber-Nd∶GdVO₄ master oscillator power amplifier［J］. Optics Communications， 2020， 460： 125109. DOI URL
[20]	NIKITOV S A， TARANOV A V， KHAZANOV E N， et al. Heat capacity and features of the phonon spectrum of single crystals of solid solutions of yttrium-lutetium aluminum garnets［J］. Acoustical Physics， 2024， 70（2）： 259-263. DOI
[21]	LIU N Q， LI N， JIANG C K， et al. Perovskite single crystals with self-cleaning surface for efficient photovoltaics［J］. Angewandte Chemie International Edition， 2024， 63（9）： e202314089.
[22]	EL-SAID A S. Fabrication of triangular pits in barium fluoride single crystals by localized electronic excitations［J］. Results in Physics， 2023， 51： 106708. DOI URL
[23]	KUZHAKOV P V， KAMANINA N V. Spectral investigations and wettability of nanostructured potassium bromide， sodium chloride， and magnesium fluoride single crystals［J］. Optics and Spectroscopy， 2014， 117（4）： 643-646. DOI URL
[24]	LI J Y， WANG C Y， LIU J H， et al. Research on quality control technology of magnetorheological ultra-precision machining of calcium fluoride crystal［J］. The International Journal of Advanced Manufacturing Technology， 2025， 139（1）： 289-311. DOI
[25]	HUANG K Y， HSU K Y， JHENG D Y， et al. Low-loss propagation in Cr⁴⁺∶YAG double-clad crystal fiber fabricated by sapphire tube assisted CDLHPG technique［J］. Optics Express， 2008， 16（16）： 12264. DOI URL
[26]	ANDREETA M R B， HERNANDES A C. Laser-heated pedestal growth of oxide fibers［M］// Springer Handbook of Crystal Growth. Berlin， Heidelberg： Springer， 2010： 393-432.
[27]	王楠楠，王　高，李仰军，等. 新型激光加热基座生长法生长氧化锆单晶光纤［J］. 激光技术， 2012， 36（1）： 19-21.
	WANG N N， WANG G， LI Y J， et al. Zirconia single crystal fiber generation based on new laser heating pedestal growth［J］. Laser Technology， 2012， 36（1）： 19-21 （in Chinese）. DOI URL
[28]	顾菊观，沈永行，陈曙英，等. LHPG法单晶光纤生长中的熔区控制技术［J］. 材料科学与工程， 2001， 19（4）： 20-23.
	GU J G， SHEN Y H， XING， et al. Molten zone controlling technique of single crystal fiber by means of LHPG growth［J］. Materials Science and Engineering， 2001， 19（4）： 20-23 （in Chinese）.
[29]	RUDOLPH P， FUKUDA T. Fiber crystal growth from the melt［J］. Crystal Research and Technology， 1999， 34（1）： 3-40. DOI URL
[30]	TAO Z X， SONG Y， XU Z W. Probing the thermally driven response of Raman-active phonon modes in sapphire single crystals by in situ Raman spectroscopy［J］. Ceramics International， 2023， 49（20）： 33175-33187. DOI URL
[31]	SAMANTA G， YECKEL A， BOURRET-COURCHESNE E D， et al. Parametric sensitivity and temporal dynamics of sapphire crystal growth via the micro-pulling-down method［J］. Journal of Crystal Growth， 2012， 359： 99-106. DOI URL
[32]	PIRZIO F， JUN S， TACCHINI S， et al. Multi-Watt amplification in a birefringent Yb∶LiLuF₄ single crystal fiber grown by micro-pulling-down［J］. Optics Letters， 2019， 44（17）： 4095-4098. DOI URL
[33]	FANG H S， YAN Z W， BOURRET-COURCHESNE E D. Numerical study of the micro-pulling-down process for sapphire fiber crystal growth［J］. Crystal Growth & Design， 2011， 11（1）： 121-129. DOI URL
[34]	BOUAITA R， ALOMBERT-GOGET G， GHEZAL E A， et al. Seed orientation and pulling rate effects on bubbles and strain distribution on a sapphire crystal grown by the micro-pulling down method［J］. CrystEngComm， 2019， 21（28）： 4200-4211. DOI URL
[35]	YOSHIKAWA A， NIKL M， BOULON G， et al. Challenge and study for developing of novel single crystalline optical materials using micro-pulling-down method［J］. Optical Materials， 2007， 30（1）： 6-10. DOI URL
[36]	SIMURA R， YOSHIKAWA A， UDA S. The radial distribution of dopant （Cr， Nd， Yb， or Ce） in yttrium aluminum garnet （Y₃Al₅O₁₂） single crystals grown by the micro-pulling-down method［J］. Journal of Crystal Growth， 2009， 311（23/24）： 4763-4769. DOI URL
[37]	XU J， SONG Q S， LIU J， et al. The micro-pulling-down growth of Eu³⁺-doped Y₃Al₅O₁₂ and Y₃ScAl₄O₁₂ crystals for red luminescence［J］. Optical Materials， 2020， 109： 110388. DOI URL
[38]	PAN Y X， LIN H， LIU J， et al. Spectroscopic properties of Yb³⁺， Ho³⁺-doped Y₃Al₅O₁₂ single crystals grown by the micro-pulling-down method［J］. Infrared Physics & Technology， 2020， 111： 103540.
[39]	ZENG Z， QIAO L， LIU Y P， et al. Numerical study on the radial dopant distribution in micro-pulling-down crystal growth［J］. Journal of Crystal Growth， 2016， 434： 110-115. DOI URL
[40]	LI L X， WAN X H， MA W H， et al. Effect of water-cooling jacket on thermal stress of large-diameter silicon grown by Czochralski method［J］. Silicon， 2024， 16（10）： 4273-4280. DOI
[41]	FANG C C， MENG B， LV G Q， et al. First-principles calculations of lightly Ga-doped monocrystalline silicon grown by Czochralski method［J］. Theoretical Chemistry Accounts， 2025， 144（3）： 22. DOI
[42]	KATYBA G M， MELIKYANTS D G， CHERNOMYRDIN N V， et al. Terahertz transmission-mode scanning-probe near-field optical microscopy based on a flexible step-index sapphire fiber［J］. Optical Engineering， 2021， 60（8）： 082010.
[43]	WANG D H， HOU W T， LI N， et al. Defects and optical property of single-crystal sapphire fibers grown by edge-defined film-fed growth method［J］. Journal of Inorganic Materials， 2020， 35（9）： 1053. DOI
[44]	舒　骏，聂玲达，赵　鹏，等. 导模法蓝宝石不同表面形貌处的晶体质量研究［J］. 人工晶体学报， 2026， 55（2）： 281-290.
	SHU J， NIE L D， ZHAO P， et al. Crystal quality of different surface morphologies in sapphire by EFG method［J］. Journal of Synthetic Crystals， 2026， 55（2）： 281-290 （in Chinese）. DOI
[45]	HE J， LI Z D， QIN Z W， et al. Etched single-crystal sapphire fiber Bragg gratings for simultaneous temperature and strain sensing at 1 500 ℃［C］// 29th International Conference on Optical Fiber Sensors. May 25-30， 2025. Porto， Portugal. SPIE， 2025： 487.
[46]	ZHU Y Z， HUANG Z Y， HAN M， et al. Fiber optic high-temperature thermometer using sapphire fiber［J］. Sensors for Harsh Environments， 2004， 5590： 19.
[47]	WANG T， GUO Q， ZHANG J， et al. Size-unlimited sapphire single-crystal fiber growth and the anisotropic & size-dependent mechanical and thermometry performance［J］. CrystEngComm， 2024， 26（40）： 5726-5733. DOI URL
[48]	黄友奇，史刘彤，高玉波，等. 蓝宝石单晶的动态力学性能及本构关系研究［J］. 硅酸盐通报， 2025， 44（9）： 3391-3401+3410. DOI
	HUANG Y Q， SHI L T， GAO Y B， et al. Dynamic mechanical property and constitutive modeling of sapphire single crystals［J］. Bulletin of the Chinese Ceramic Society， 2025， 44（9）： 3391-3401+3410 （in Chinese）. DOI
[49]	GAO X L， MA R， FU S N， et al. Mechanical properties and deformation mechanisms of single-crystal silicon tested by nanoindentation and scratch［J］. International Journal of Applied Mechanics， 2025， 17（10）： 2550084.
[50]	ZHENG L X， MEI L C， ZHU Z J， et al. Growth and scintillation performance of Tb/Dy∶YAG， Tb/Dy/Lu∶YAG and Tb/Dy/Ce∶YAG crystals for X-ray imaging applications［J］. Radiation Physics and Chemistry， 2026， 242： 113655. DOI URL
[51]	MORETTO S， MADDEN A， QUARÀ A， et al. In vitro comparative analysis of ablation volume and energy requirements for 1 mm³ stone ablation using Ho∶YAG， p-Tm∶YAG， and TFL lasers［J］. Urolithiasis， 2025， 53（1）： 194. DOI
[52]	QUARÀ A， BRAVO-BALADO A， MORETTO S， et al. In vitro ablation rates of Ho∶YAG， p-Tm∶YAG and TFL lasers［J］. World Journal of Urology， 2025， 43（1）： 685. DOI
[53]	PULLAR R C， TAYLOR M D， BHATTACHARYA A K. Effect of sodium on the creep resistance of yttrium aluminium garnet （YAG） fibres［J］. Journal of the European Ceramic Society， 2006， 26（9）： 1577-1583. DOI URL
[54]	FARHI H， LEBBOU K， BELKAHLA S， et al. Fiber single crystal growth by LHPG technique and optical characterization of Ce³⁺-doped Lu₂SiO₅ ［J］. Optical Materials， 2008， 30（9）： 1461-1467. DOI URL
[55]	MAO R H， ZHANG L Y， ZHU R Y. Search for scintillation in doped lead fluoride crystals［C］// 2009 IEEE Nuclear Science Symposium Conference Record （NSS/MIC）. October 24 - November 1， 2009， Orlando， FL， USA. IEEE， 2010： 2182-2186.
[56]	KUROSAWA S， YANAGIDA T， YOKOTA Y， et al. Crystal growth and scintillation properties of fluoride scintillators［J］. IEEE Transactions on Nuclear Science， 2012， 59（5）： 2173-2176. DOI URL
[57]	孟　宗，陈子君，李玉和，等. 石英包层LYSO∶Ce闪烁光纤的电子辐射传感特性［J］. 中国激光， 2020， 47（8）： 804004.
	MENG Z， CHEN Z J， LI Y H， et al. Electron radiation sensing characteristics of silica cladding LYSO∶Ce scintillating fiber［J］. Chinese Journal of Lasers， 2020， 47（8）： 804004 （in Chinese）. DOI URL
[58]	MEZEIX L， GREEN D J. Comparison of the mechanical properties of single crystal and polycrystalline yttrium aluminum garnet［J］. International Journal of Applied Ceramic Technology， 2006， 3（2）： 166-176. DOI URL
[59]	DAI Z H， DOYLE M C， LIU X， et al. The mechanical behavior of metal-halide perovskites： elasticity， plasticity， fracture， and creep［J］. Scripta Materialia， 2023， 223： 115064. DOI URL