CeF3 Crystals Research Articles

Optical properties of CeF3 crystal at high temperature or pressure by first principles and its application in isolators

In this work, CeF3 single crystal was successfully grown by Bridgman method. The XRD diffraction was tested and the data matched well with the standard card. Further trying its optical performance, CeF3 single crystal has very high transmittance of 90 %, the cut-off absorption edge length of the crystal is better than 300 nm. Testing the magneto-optical Verdet constant of CeF3 single crystal and trial-produced optical isolator shows that the Verdet constants of CeF3 single crystals in the magneto-optical field are similar to those of TGG crystals. The band structure, state density, optical properties and elastic constants of CeF3 crystal under different temperature and pressure are calculated by first principles. The results show that CeF3 crystal has excellent thermal stability and mechanical stability. Under high temperature conditions, light absorption and loss are small, and the optical properties are stable. Under high pressure, the crystal exhibits certain stability and impact resistance, and the optical properties are relatively stable. The results show that CeF3 crystal has significant advantages in replacing TGG crystal in laser field, and has a certain application prospect in window materials.

Optical characteristics and energy transfer analysis of Dy3+-Pr3+ ions doped in CeF3 crystal

The Dy,Pr:CeF3 single crystal was successfully grown and its optical characteristics were investigated systematically. The analysis of energy transfer process between Dy3+ and Pr3+ in CeF3 crystal was also carried out. The XRD study shows the crystal belongs to the hexagonal crystal system and its lattice parameters are a = 7.1252 Å and c = 7.2775 Å. The maximum phonon energy of the crystal was speculated to be 377.1 cm−1 by Raman spectrum. The absorption coefficient at 442 nm of Dy,Pr:CeF3 crystal is 0.89 cm−1. The radiative lifetime of Dy:4F9/2 level is 2.08 ms and the one of Pr:3P0 level is 145.25 μs in Dy,Pr:CeF3 crystal obtained by J-O theory calculation. The maximum emission cross-section of Dy: 4F9/2 → 6H13/2 transition is calculated to be ∼0.15 × 10−20 cm2 in the crystal. The fluorescence lifetimes of Dy:4F9/2, Pr:3P0 and Pr:1D2 levels are estimated to be ∼1.25 ms, ∼17.91 μs and ∼112.37 μs, respectively. The results show that Dy,Pr:CeF3 crystal not only owns a larger absorption coefficient at 442 nm than Dy:CeF3 crystal, but also holds the much longer lifetime of Pr:3P0 level than Pr:CeF3 crystal because of the energy transfer in Dy3+-Pr3+.

Spectroscopic and magneto-optical properties of novel bifunctional Nd,Er:CeF3 crystal

In this study, we report a successful Bridgman growth of Nd3+ and Er3+ co-doped CeF3 (Nd,Er:CeF3) single crystal with a size of Ø25 mm × 30 mm. The absorption and fluorescence characteristics of the Nd,Er:CeF3 crystal were studied systematically. The results show that the fluorescence emission peaks were positioned at 547, 669, 1062.6, and 1542.6 nm, respectively. The fluorescence lifetimes centered at 1062.6 and 1542.6 nm for Nd3+ and Er3+ were 0.313 and 1.12 ms, respectively. Meanwhile, the spectroscopic properties of Nd,Er:CeF3 crystals were investigated based on the Judd–Ofelt theory. Notably, the magneto-optical performance of the Nd,Er:CeF3 crystal was investigated for the first time. The Verdet constants of the Nd,Er:CeF3 crystal at 532, 632.8, 1064, and 1310 nm are 220.3, 142.4, 40.7, and 23.1 rad T−1 m−1, respectively, which are significantly higher than those of undoped CeF3 and traditional Tb3Ga5O12. The results show that Nd,Er:CeF3 is a bifunctional crystal with potential applications in laser and magneto-optical fields.

Novel Nd3+ and Ho3+ co-doped multifunctional CeF3 crystal for laser and magneto-optical applications

In this study, a 1.5 at.% Nd3+ and 0.5 at.% Ho3+ co-doped CeF3 (Nd,Ho:CeF3) single crystal was successfully grown by the vertical Bridgman method. The absorption and fluorescence characteristics of the fabricated crystal were evaluated. The spectroscopic properties of the Nd,Ho:CeF3 crystal were investigated based on the Judd–Ofelt (J–O) theory. The parameters Ω2, Ω4, and Ω6 of Ho3+ were fitted as 0.338 × 10−20, 0.731 × 10−20, and 0.350 × 10−20 cm2, respectively. The fluorescence lifetimes centered at 1064 and 1970 nm for Nd3+ and Ho3+ were 261 and 47 μs, respectively. Notably, the magneto-optical performance of the Nd,Ho:CeF3 crystal was investigated for the first time. The measured Verdet constants of Nd,Ho:CeF3 at 532, 632.8, 1064, 1310, and 1550 nm were 228.0, 154.7, 42.4, 29.1, and 18.5 rad·T−1·m−1, respectively, which were significantly larger than those of pure CeF3 and traditional Tb3Ga5O12. The results demonstrated that Nd,Ho:CeF3 crystals can be applied in both lasers and magneto-optical devices.

Pr3+-doped CeF3 crystals: Analysis of optical traits and fluorescence from Pr3+: 1D2 level for visible and near-infrared lasers

In this work, four Pr3+ -doped CeF3 crystals with 0.2, 0.4, 0.6, and 0.8 at.% Pr3+ ion doping levels nominally in the melt have been successfully grown, and their absorption and emission spectra, including fluorescence decay times were analyzed. Especially, yellow and near-infrared (NIR) emissions originating from Pr3+: 1D2 level were explored in detail. In comparison, 0.2 at.% Pr3+-doped sample showed better spectral parameters in all studied crystals. In such a crystal, at 443 nm wavelength, the derived absorption cross-section (σabs) is 0.88 × 10-20 cm2 with full width at half maximum (FWHM) ∼ 10 nm in π polarization direction, whereas σabs is 1.32 × 10-20 cm2 with FWHM ∼ 6.7 nm in σ polarization direction at the same wavelength. Likewise, the calculated emission cross-section (σem) for 594 nm wavelength is 0.69 × 10-20 cm2 in π direction and 0.46 × 10-20 cm2 in σ direction. Also, acquired σem at 790, 755, 1014, and 1432 nm wavelengths is 6.15 × 10-21 cm2, 7.33 × 10-21 cm2, 7.66 × 10-21 cm2, and 6.56 × 10-21 cm2 individually. Here evaluated fluorescence decay time of 1D2 level is ∼ 200.6 μs. Obtained higher σabs, larger σem, and higher luminescence decay rates of 0.2 at.% Pr: CeF3 crystal specify its potential as a gain medium for orange and NIR lasers.

Yb3+, Er3+: CeF3 crystals: Growth, first-principles simulation, and near-infrared optical properties

Yb3+, Er3+: CeF3 crystals were successfully grown via Bridgman-Stockbarger technique, and their structure and physicochemical properties were characterized and analyzed. The results have shown that the maximum phonon vibrational frequency of the crystals is 391 cm−1. Under 980 nm excitation, Yb3+ ions doping can effectively improve the luminescence intensity at 1550 nm. The maximum luminescence intensity was achieved at the Yb3+ ion concentration of 3 at.%. The energy transfers, concentration quenching mechanisms and the factors affecting the fluorescence decay time were investigated in detail. The band gap structure, density of states and charge distribution of Yb3+, Er3+: CeF3 crystals were studied in depth by first principles simulation. This work proves that Yb3+, Er3+: CeF3 crystals have great potential for the near-infrared laser applications.

Growth, first-principles simulations and near-infrared optical properties of rare earth (Nd3+, Er3+)-doped CeF3 crystals for laser applications

Growth, first-principles simulations and near-infrared optical properties of rare earth (Nd3+, Er3+)-doped CeF3 crystals for laser applications

Measurement of residual [formula omitted] polarization in various scintillating materials to search for [formula omitted]-violating [formula omitted] polarization in [formula omitted] decay

A new experimental method to search for T-violating transverse muon polarization (PT) in the K+→π0μ+ν (Kμ3) decay using a segmented CeF3 calorimeter has been proposed. One of the key issues for this experiment is the choice of a scintillation material which can maintain the μ+ spin polarization for several μ+ lifetimes. The residual μ+ polarization in a CeF3 scintillating crystal was previously measured at the J-PARC Material and Life Science Facility (MLF). Unfortunately, due to the small size of the CeF3 material, beam backgrounds contributed significantly to the μSR spectra, and the absolute μ+ polarization could not be determined accurately. In order to solve this problem, a new experiment was performed at the MLF using a large CeF3 crystal, which successfully reduced the beam backgrounds to a negligible level. The residual μ+ polarization in CeF3 was measured by changing the strength of the applied longitudinal field (LF). The polarization was obtained to be 90 ± 2% with LF = 140 Gauss, which is high enough to perform the new T-violation experiment.

Measurement of non-linearity in the cathodoluminescence yield for non-doped scintillators

We propose a method for studying nonlinearity in the cathodoluminescence (CL) characteristics of wide-bandgap materials based on the measurements of the CL energy dependence on the total energy of a pulsed electron beam Eb using its bremsstrahlung. It is shown that the x-ray radiant energy produced by a high-power (∼10MW/cm2) electron beam with particle energies of 50–300 keV is proportional to Eb in the case of weak variations in the electron energy distribution of the beam. This direct proportionality between Eb and the x-ray radiant energy is experimentally confirmed in the current experiment by measuring the dependence of the molecular nitrogen emission radiant energy at 337 nm excited by a direct electron impact (the 0-0 vibrational transition of the second positive system of the emission bands of N2 molecule) on the total electron beam energy Eb. Using this result, the dependencies of the CL radiant energy on Eb are studied for undoped Bi4Ge3O12, PbWO4, CeF3, and BaF2 crystals with bright intrinsic luminescence. An interpretation of these dependencies is given using a simple theoretical model and photoluminescence nonlinearity data published in the literature. We estimate the average concentration of the electronic excitations (EE) provided by the electron beam (1018–1019 e.–h.p./cm3) and obtain the approximate dependencies of the CL yield on the EE density for the studied materials. For the CeF3 crystal, different CL yield dependencies on the EE density are found for the bands at 300 and 350 nm.

Spectroscopic and magneto-optical characteristics of erbium doped cerium trifluoride crystal grown by the Bridgman method

In this study, a 2 at% erbium doped cerium trifluoride (Er:CeF3) single crystal was grown using the Bridgman method. The consequent absorption, infrared transmittance, and fluorescence spectra were recorded. The spectroscopic properties of Er:CeF3 crystals were intensively studied based on the Judd–Ofelt (J–O) theory. The Ω2, Ω4, and Ω6 parameters were fitted to be 5.206 × 10−20, 1.805 × 10−20, and 3.06 × 10−20 cm2, respectively. The emission cross-section centered at 1564.6 nm was calculated to be 1.053 × 10−20 cm2, and the corresponding fluorescence lifetime was measured to be 1.675 ms. Additionally, the magneto-optical (MO) performance of the Er:CeF3 crystal was investigated for the first time. The Verdet constants of Er:CeF3 at 532, 632.8, 1064, and 1310 nm are 231.0, 165.4, 43.4, and 24.4 rad·T−1·m−1, respectively, which are significantly higher than those of pure CeF3 and traditional Tb3Ga5O12. The results show that the Er:CeF3 crystal can be applied both to solid-state lasers and Faraday devices.

Energy Structure and Luminescence of CeF3 Crystals

The results of the calculation of the energy band structure and luminescent research of CeF3 crystals are presented. The existence of two 5d1 and 5d2 subbands of the conduction band genetically derived from 5d states of Ce3+ ions with different effective electron masses of 4.9 me and 0.9 me, respectively, is revealed. The large electron effective mass in the 5d1 subband facilitates the localization of electronic excitations forming the 4f-5d cerium Frenkel self-trapped excitons responsible for the CeF3 luminescence. The structure of the excitation spectra of the exciton luminescence peaked at 290 nm, and the defect luminescence at 340 nm confirms the aforementioned calculated features of the conduction band of CeF3 crystals. The peculiarities of the excitation spectra of the luminescence of CaF2:Ce crystals dependent on the cerium concentration are considered with respect to the phase formation possibility of CeF3.

Bridgman Growth and Physical Properties Anisotropy of CeF3 Single Crystals

Bulk c-oriented CeF3 single crystals (sp. gr. P3¯c1) were grown successfully by the vertical Bridgman technique in a fluorinating atmosphere. A description of the crystal growth procedure and the solution of the difficulties during the growth process are presented in detail. The anisotropy of the mechanical, thermal and electrophysical properties were studied for the first time. The maximum values of the thermal conductivity coefficient (α = 2.51 ± 0.12 W·m−1·K−1) and the ionic conductivity (σdc = 2.7 × 10−6 S/cm) at room temperature are observed in the [0001] direction for the CeF3 crystals. The Vickers (HV) and Berkovich (HB) microhardnesses for the (0001), (101¯0) and (112¯0) crystallographic planes were investigated. The HB values were higher than the HV ones and decreased from 3.8 to 2.9 GPa with an increase in the load in the range of 0.5–0.98 N for the hardest (0001) plane. The {112¯0}, {101¯0} and {0001} cleavage planes were observed during the indentation process of the CeF3 crystals. The variability of Young’s, the shear modules and Poisson’s ratio were analyzed. A significant correlation between the shapes of the Vickers indentation patterns with Young’s modulus anisotropy was found. The relationship between the anisotropy of the studied properties and the features of the CeF3 trigonal crystal structure is discussed.

Magneto-optical performances of novel neodymium-doped CeF3 crystal

The highly transparent neodymium-doped CeF3 (Nd:CeF3) single crystal with diameter of 20 mm × 35 mm was grown by the Bridgman Stockbarger (BS) method. The optical and magneto-optical (MO) performances of Nd:CeF3 were experimentally investigated in UV–Vis and near-IR spectral range. Notably, Nd:CeF3 exhibits high transparency and significantly enhanced Faraday rotation. Compared with commercial terbium gallium garnet (TGG), Nd:CeF3 has higher Verdet constants at different measured wavelengths. The bulk laser-induced damage of c-cut Nd:CeF3 crystal was also determined by R-on-1 method. All the results demonstrate that the properties of Nd:CeF3 are superior to those of CeF3 and TGG. The excellent MO properties of Nd:CeF3 with a used wavelength of 0.3–2.2 µm are especially important for high power isolators in order to cover UV–Vis and the entire near-IR range.

TGT growth and magneto-optical properties of PrF3 crystal

High quality PrF3 crystal was successfully grown by the temperature gradient technique (TGT). The magneto-optical properties of PrF3 crystal were systematically investigated in the UV-VIS-NIR region. The advantage of PrF3 over CeF3 and TGG is its transparency in deep-UV region down to 258 nm. The dispersions of Verdet constant of PrF3 and TGG crystals in VIS-NIR region are similar. The Verdet constant of PrF3 crystal can theoretically increase from 677.93 rad T−1•m−1 at 300 nm to 967.53 rad T−1•m−1 at 270 nm. The CeF3 and TGG crystals aren't transparent in this region. Therefore, PrF3 crystal is the promising candidate for use as a Faraday rotator for optical systems operating below 300 nm.

Анизотропия анионной проводимости в монокристаллах суперионного проводника CeF-=SUB=-3-=/SUB=-

The anisotropy of anionic conductivity in crystals of a superionic conductor CeF3 with the tysonite structure (sp. gr. P-3с1) has been studied for the first time. The conductivity measurements at temperatures from 300 K to 600 K were carried out along the principal a- and c-axes of trigonal unit cell of the crystal. The maximum value of electrical conductivity is observed along the c-axis. The superionic CeF3 crystals have the weak anisotropy of electrical conductivity equal to σ||c/σ||a = 2.4 and σ||c = 5.6 10–4 S/cm at 500 K. The anisotropy effect of anionic conductivity in individual fluorides with the tysonite structure is discussed in connection with the peculiarities of their atomic structure.

Faraday Rotation of Dy2O3, CeF3 and Y3Fe5O12 at the Mid-Infrared Wavelengths

The relatively narrow choice of magneto-active materials that could be used to construct Faraday devices (such as rotators or isolators) for the mid-infrared wavelengths arguably represents a pressing issue that is currently limiting the development of the mid-infrared lasers. Furthermore, the knowledge of the magneto-optical properties of the yet-reported mid-infrared magneto-active materials is usually restricted to a single wavelength only. To address this issue, we have dedicated this work to a comprehensive investigation of the magneto-optical properties of both the emerging (DyO ceramics and CeF crystal) and established (YFeO crystal) mid-infrared magneto-active materials. A broadband radiation source was used in a combination with an advanced polarization-stepping method, enabling an in-depth analysis of the wavelength dependence of the investigated materials’ Faraday rotation. We were able to derive approximate models for the examined dependence, which, as we believe, may be conveniently used for designing the needed mid-infrared Faraday devices for lasers with the emission wavelengths in the 2- spectral region. In the case of YFeO crystal, the derived model may be used as a rough approximation of the material’s saturated Faraday rotation even beyond the 2- wavelengths.

Temperature-dependent terahertz dielectric modulation of a high-performance magneto-optic CeF3 crystal

We present experimental observations of the high-performance magneto-optic (MO) CeF3 crystal using terahertz time-domain spectroscopy (THz-TDS) in the temperature range 40–300 K for the first time. The complex refractive index strongly depends on temperature, which increases with increasing temperature. Intriguingly, the changes of complex refractive index values reach more than 0.1 between 40 K and 300 K, which is larger than terbium scandium aluminum garnet (TSAG) crystal. The weak loss tangent indicates that the crystal has a high potential as a high-dielectric-constant photovoltaic device in the terahertz domain.

Growth, thermal, and polarized spectroscopic properties of Nd:CeF3 crystal for dual-wavelength lasers

A Nd:CeF3 crystal was grown successfully by the vertical Bridgman method. The polarized optical properties were investigated for the first time. Based on the Judd–Ofelt theory, the spectral parameters of Nd3+ were studied in detail by using the spectrum of the as-grown crystal. The peak absorption cross-section of σ-polarization at 791 nm is 1.59 × 10−20 cm2, the full width at half maximum (FWHM) is 10 nm. The peak emission cross-section of σ-polarization at 1070 nm is approximately 2.53 × 10−20 cm2, and the three peaks that make up the broadband peak have comparable value. The measured 4F3/2 level fluorescence lifetime is 0.406 ms. Moreover, segregation coefficient of Nd3+, thermal diffusivity coefficient, and thermal conductivity were also measured. We propose that the Nd:CeF3 crystal may be a promising material for 1 μm dual-wavelength laser applications.

Spectral-Kinetic Properties and Energy Transfer in Nanoparticles of Y0.5–xCe0.5TbxF3 Solid Solution

Crystalline nanoparticles of Y0.5–xCe0.5TbxF3, doped with various concentrations (x = 0, 0.005, 0.01, 0.05, 0.1, 0.15, and 0.2) of Tb3+ ions were synthesized by co-precipitation. The crystal structure and chemical composition of nanoparticles were studied using transmission electron microscopy, scanning electron microscopy, and X-ray diffractometry. The obtained nanoparticles of solid solutions had an elliptical shape with a size of 10–15 nm along the long axis and good crystallinity with the structure of a CeF3 crystal. The spectral-kinetic properties of the obtained nanoparticles, and the effect of the concentration of Tb3+ activator ions on the energy transfer from Ce3+ to Tb3+ ions were investigated. Energy transfer from Ce3+ to Tb3+ ions in nanocrystals of the Y0.5–xCe0.5TbxF3 solid solutions occurs mainly through the dipole–dipole interaction. The results of evaluating the efficiency of energy transfer from Ce3+ to Tb3+ ions show its increase with increasing concentration of Tb3+ ions.

Growth and mid-infrared luminescence property of Ho3+ doped CeF3 single crystal

A Ho3+-doped CeF3 crystal was successfully grown for the first time using the Bridgman method, and its spectral properties were studied. By analyzing the absorption and emission measurements of the Ho:CeF3 crystal with the Judd–Ofelt theory, the intensity parameters Ω2,4,6, emission cross-sections, gain cross-sections, and excited state lifetimes were calculated. It was found that the peak absorption cross-section around 447 nm is 0.4339 × 10−20 cm2, which matched to the commercially available blue laser diode lasers. The 2.0 μm excitation emission of the Ho:CeF3 crystal corresponding to the stimulated emission Ho3+:5I7→5I8 transition has an emission cross section of 0.24 × 10−20 cm2 with FWHM of 146 nm.