Thin film magneto‐optical (MO) materials are enablers for integrated nonreciprocal photonic devices such as isolators and circulators. Films of polycrystalline bismuth‐substituted yttrium iron garnet ...(Bi:YIG) have been grown on silicon substrates and waveguide devices, in which an yttrium iron garnet (YIG) seedlayer is placed either above or below the active Bi:YIG layer to promote crystallization. The films exhibit a high MO figure of merit of up to 769° dB−1 at 1550 nm wavelength. Growth of single phase Bi:YIG on the sidewalls of waveguides is demonstrated, which can be used in nonreciprocal transverse electric (TE)‐mode devices.
This work presents developments in the integration of magneto‐optical materials into photonic circuits. Successful demonstration of top‐down crystallized bismuth‐substituted yttrium iron garnet films on silicon is shown, leading to figures of merit at 1550 nm above one order of magnitude higher than previously reported values for polycrystalline garnets. Sidewall growth of garnets, essential for transverse electric‐mode isolators, is also demonstrated.
Inorganic solid fast Li+ conductors based batteries are expected to overcome the limitations over safety concerns of flammable organic polymer electrolytes based Li+ batteries. Hence, an ...all-solid-state Li+ battery using non-flammable solid electrolyte have attracted much attention as next-generation battery. Therefore, in the development of all-solid-state lithium rechargeable batteries, it is important to search for a solid electrolyte material that has high Li+ conductivity, low electronic conductivity, fast charge transfer at the electrode interface and wide electrochemical window stability against potential electrodes and lithium metal. Hence, significant research effort must be directed towards developing novel fast Li+ conductors as electrolytes in all-solid-state lithium batteries. Among the reported inorganic solid Li+ conductive oxides, garnet-like structural compounds received considerable attention in recent times for potential application as electrolytes in all-solid-state lithium batteries. The focus of this review is to provide comprehensive overview towards the importance of solid fast lithium ion conductors, advantages of lithium garnets over other ceramic lithium ion conductors and understanding different strategies on synthesis of lithium garnets. Attempts have also been made to understand relationship between the structure, Li+ conduction and Li+ dynamics of lithium garnets. The status of lithium garnets as solid electrolyte in electrochemical devices like all-solid state lithium battery, lithium-air battery and sensor are also discussed.
In this work, we investigated the effect of Rb and Ta doping on the ionic conductivity and stability of the garnet Li7+2x–y (La3–x Rb x )(Zr2–y Ta y )O12 (0 ≤ x ≤ 0.375, 0 ≤ y ≤ 1) superionic ...conductor using first principles calculations. Our results indicate that doping does not greatly alter the topology of the migration pathway, but instead acts primarily to change the lithium concentration. The structure with the lowest activation energy and highest room temperature conductivity is Li6.75La3Zr1.75Ta0.25O12 (E a = 19 meV, σ300K = 1 × 10–2 S cm–1). All Ta-doped structures have significantly higher ionic conductivity than the undoped cubic Li7La3Zr2O12 (c-LLZO, E a = 24 meV, σ300K = 2 × 10–3 S cm–1). The Rb-doped structure with composition Li7.25La2.875Rb0.125Zr2O12 has a lower activation energy than c-LLZO, but further Rb doping leads to a dramatic decrease in performance. We also examined the effect of changing the lattice parameter at fixed lithium concentration and found that a decrease in the lattice parameter leads to a rapid decline in Li+ conductivity, whereas an expanded lattice offers only marginal improvement. This result suggests that doping with larger cations will not provide a significant enhancement in performance. Our results find higher conductivity and lower activation energy than is typically reported in the experimental literature, which suggests that there is room for improving the total conductivity in these promising materials.
This article is devoted to the experimental investigation of the occurrence of the so-called "low-temperature Belov point" <inline-formula> <tex-math notation="LaTeX">T_{B} ...</tex-math></inline-formula> predicted previously for the mixed rare earth-yttrium iron garnet compounds RE<inline-formula> <tex-math notation="LaTeX">_{x}Y_{\mathrm {3 - {}}x} </tex-math></inline-formula>Fe 5 O 12 possessing or not a magnetic compensation point <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {comp}} </tex-math></inline-formula>. Isothermal magnetizations <inline-formula> <tex-math notation="LaTeX">M_{T}(H) </tex-math></inline-formula> of two single crystals of Tb<inline-formula> <tex-math notation="LaTeX">_{x}Y_{3-x} </tex-math></inline-formula>Fe 5 O 12 with rare-earth (RE) = Tb, and <inline-formula> <tex-math notation="LaTeX">x = 1.98 </tex-math></inline-formula>, 0.37, were measured in the 4.2-300 K range, using dc magnetic field <inline-formula> <tex-math notation="LaTeX">H </tex-math></inline-formula> up to 100 kOe applied in one or more of the three main crystallographic directions. Anomalies are observed in the region of <inline-formula> <tex-math notation="LaTeX">T_{B}^{\mathrm {TbIG}} \approx 58 </tex-math></inline-formula> K, the previous estimated value for TbIG (<inline-formula> <tex-math notation="LaTeX">x = 3 </tex-math></inline-formula>), in the temperature dependences of the paraprocess susceptibility <inline-formula> <tex-math notation="LaTeX">\chi _{p} </tex-math></inline-formula>, the parameter <inline-formula> <tex-math notation="LaTeX">\vert b\vert </tex-math></inline-formula> of the bH 2 term of the quadratic expansion of <inline-formula> <tex-math notation="LaTeX">M_{T}(H) </tex-math></inline-formula> curves, and other pertinent magnetic characteristics. For <inline-formula> <tex-math notation="LaTeX">x = 1.98 </tex-math></inline-formula> with <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {comp}} = 137 </tex-math></inline-formula> K and when <inline-formula> <tex-math notation="LaTeX">H </tex-math></inline-formula> is applied along <inline-formula> <tex-math notation="LaTeX">\langle 110\rangle </tex-math></inline-formula>, the <inline-formula> <tex-math notation="LaTeX">\chi _{p} </tex-math></inline-formula>- and <inline-formula> <tex-math notation="LaTeX">\vert b\vert </tex-math></inline-formula>-maxima take place close to <inline-formula> <tex-math notation="LaTeX">T_{B}^{\mathrm {TbIG}} </tex-math></inline-formula>. The anisotropy of the <inline-formula> <tex-math notation="LaTeX">\chi _{p} </tex-math></inline-formula>-data gives evidence for a spontaneous noncollinear structure around the easy axis of magnetization <inline-formula> <tex-math notation="LaTeX">\langle 111\rangle </tex-math></inline-formula> at 4.2 K. For <inline-formula> <tex-math notation="LaTeX">x = 0.37 </tex-math></inline-formula> which has no <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {comp}} </tex-math></inline-formula> point and when <inline-formula> <tex-math notation="LaTeX">H </tex-math></inline-formula> is applied along <inline-formula> <tex-math notation="LaTeX">\langle 100\rangle </tex-math></inline-formula>, the <inline-formula> <tex-math notation="LaTeX">\chi _{p} </tex-math></inline-formula>- and <inline-formula> <tex-math notation="LaTeX">\vert b\vert </tex-math></inline-formula>-maxima are clearly disturbed by the sign anomalies caused by the noncollinear structure instability mechanism due to the crossing of the Tb 3+ levels at the critical point <inline-formula> <tex-math notation="LaTeX">T^{\ast } = 16 </tex-math></inline-formula> K and by the lower continuous change from the easy axis to a low-symmetry angular phase <inline-formula> <tex-math notation="LaTeX">\langle </tex-math></inline-formula>uuw<inline-formula> <tex-math notation="LaTeX">\rangle </tex-math></inline-formula> due to the first spontaneous spin reorientation phase transition at <inline-formula> <tex-math notation="LaTeX">T_{\mathrm {SR1}} = 40 </tex-math></inline-formula> K. When <inline-formula> <tex-math notation="LaTeX">x </tex-math></inline-formula> decreases from 3 to 0.37, it is found that despite different anisotropy effects of the Tb 3+ ion, its magnetic moment <inline-formula> <tex-math notation="LaTeX">m_{\mathrm {Tb}} </tex-math></inline-formula> close to <inline-formula> <tex-math notation="LaTeX">T_{B}^{\mathrm {TbIG}} </tex-math></inline-formula> is practically constant (~4.99 in <inline-formula> <tex-math notation="LaTeX">\mu _{B} </tex-math></inline-formula> per Tb 3+ ion).
•Two Te6+-containing garnet ceramics Li3Y3Te2O12 and Li3Yb3Te2O12 were prepared by the solid-state reaction method at low firing temperatures below 960 °C.•Good microwave dielectric properties of εr ...=7.83, Q × f =47,800 GHz (13 GHz), τf = –47 ppm/°C for Li3Y3Te2O12, and εr =5.94, Q × f =41,800 GHz (at 15 GHz), τf = –76 ppm/°C for Li3Yb3Te2O12 were obtained.•The good chemical compatibility of Li3A3Te2O12 (A =Y, Yb) ceramics with Ag electrodes indicated their promising potential as candidates for LTCC technology applications.
Te6+-containing microwave dielectric ceramics Li3A3Te2O12 (A = Y, Yb) with low firing temperatures were prepared using the solid-state reaction method. Li3Y3Te2O12 and Li3Yb3Te2O12 can be obtained as garnet single-phase ceramics with low sintering temperatures of 940 ℃ and 950 ℃, respectively. The cations, such as Li+, Te6+, and Y3+/Yb3+, fully occupied the tetrahedral, octahedral, and dodecahedral sites of garnet structure, respectively. Li3A3Te2O12 (A = Y, Yb) ceramics exhibit εr ∼ 7.83 ± 0.2 and 5.94 ± 0.2, Q × f ∼ 47,800 ± 500 GHz and 41,800 ± 500 GHz, and τf ∼ –47 ± 3.0 ppm/°C and –76 ± 3.0 ppm/°C, respectively. The full width at half-maximum (FWHM) values of the A1g Raman mode correlate negatively with the Q × f values. Moreover, Li3A3Te2O12(A = Y, Yb) ceramics possess good chemical compatibility with the Ag electrode, making them promising candidates for low-temperature cofired ceramics (LTCC) technologies.
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•Diamondiferous kimberlites in the southern part of Siberian craton characterized by high TiO2 and high mg# values in garnet xenocrysts.•Titanium in garnets is indicator of ...inhomogeneous composition of sub-continental lithospheric mantle.•High-Ti in garnets and high-Ti in kimberlites are result of asthenosphere activity SCLM under northern part of Siberian craton is generally poor in Ti.
This contribution reports some 16,000 major and minor element analyses of garnet xenocrysts derived from 18 (out of the 21 known) kimberlite fields of the Yakutian Kimberlite Province (YaKP) on the Siberian craton in Russia. Using TiO2–in–garnet as an indicator of heterogeneity within the subcontinental lithospheric mantle (SCLM), as well as garnet mg# (mg#=Mg2+/(Mg2++Fe2+)*100), we distinguish three subpopulations of garnet: 1) high content of TiO2 (0.26–0.50 wt%) and high mg# (80.6–82.6) garnet xenocrysts are common in the southern diamondiferous kimberlite fields; 2) garnet xenocrysts with low content of TiO2 (0.06–0.26 wt%) and relatively high values of mg# (78.8–81.7), which prevail in the northern ‘barren’ kimberlite fields; and 3) three anomalous northern kimberlite fields (Chomurdakh, Ogoner-Yuryakh, Toluopka) characterized by the predominance of garnet xenocrysts with high TiO2 content (0.53–0.78 wt%) at relatively low mg# (76.9–78.3).
It is reasonable to assume that relatively thin cratonic mantle lithosphere beneath the three anomalous kimberlite fields underwent intense metasomatic overprinting by melts and fluids injected from the underlying asthenosphere, which changed the compositions of peridotitic garnets significantly. An interpretation of the data presented in this study is that the generally high TiO2 contents of kimberlites in the northern YaKP (>1.5 wt% TiO2) are a primary magmatic feature of asthenospheric origin because the lithospheric mantle traversed by these kimberlite magmas is TiO2 depleted. We propose a model in which the relatively thin SCLM of the northern Siberian craton provided less opportunity for high-TiO2 asthenospheric kimberlite melts to interact and change compositions on their way to the Earth’s surface. The high-TiO2 kimberlites of the northern YaKP may thus represent a good approximation of the primary compositions of natural kimberlite melts.
Garnets have the general formula of A
3
B
2
C
3
O
12
and form a wide range of inorganic compounds, occurring both naturally (gemstones) and synthetically. Their physical and chemical properties are ...closely related to the structure and composition. In particular, Ce
3+
-doped garnet phosphors have a long history and are widely applied, ranging from flying spot cameras, lasers and phosphors in fluorescent tubes to more recent applications in white light LEDs, as afterglow materials and scintillators for medical imaging. Garnet phosphors are unique in their tunability of the luminescence properties through variations in the {A}, B and (C) cation sublattice. The flexibility in phosphor composition and the tunable luminescence properties rely on design and synthesis strategies for new garnet compositions with tailor-made luminescence properties. It is the aim of this review to discuss the variation in luminescence properties of Ce
3+
-doped garnet materials in relation to the applications. This review will provide insight into the relation between crystal chemistry and luminescence for the important class of Ce
3+
-doped garnet phosphors. It will summarize previous research on the structural design and optical properties of garnet phosphors and also discuss future research opportunities in this field.
Crystal chemistry, luminescence and applications of Ce
3+
-doped garnets are reviewed and the tuning of optical properties is explained
via
combined insights from experiments and theory.
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