Gradient refractive index structure of phosphor‐in‐glass coating for packaging of white <scp>LED</scp>s

Xu, Xujia; Li, Hong; Zhuo, Yong; Xiong, Dehua; Chen, Mingxiang

doi:10.1111/jace.16031

Cited by 23 publications

(16 citation statements)

References 54 publications

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“…4(a), which represents the polar nano-domains at room temperature. The average size of these polar nano-domains is less than 5 nm and consistent with its presence below the Burns temperature [32][33][34][35]. Figure 4 been reported for the PMN [32][33][34][35].…”

Section: Temsupporting

confidence: 70%

“…The average size of these polar nano-domains is less than 5 nm and consistent with its presence below the Burns temperature [32][33][34][35]. Figure 4 been reported for the PMN [32][33][34][35]. It is believed that Co and Nb are present in alternate layers stacked along <111> as reported by the 'random layer model' [34,35].…”

Section: Temsupporting

confidence: 67%

“…Figure 4 been reported for the PMN [32][33][34][35]. It is believed that Co and Nb are present in alternate layers stacked along <111> as reported by the 'random layer model' [34,35]. Nonstoichiometric ordering of the PMN should be different than the ordering of the PCN because two different oxidation states of the Co-ion is known to be quite stable.…”

Section: Temmentioning

confidence: 97%

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Investigation of re-entrant relaxor behaviour in lead cobalt niobate ceramic

et al. 2019

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The temperature dependent dielectric properties revealed re-entrant relaxor behaviour (T m ~130 K and 210 K for 1 kHz) below a high temperature diffused phase transition, T c ~270 K in lead cobalt niobate (PCN). Multiple positive/negative magnetodielectric effect and deviation from straight line at ~130 K is observed in temperature dependence of inverse susceptibility, which depicts origin of frustration. Microstructure examination depicts closely packed grains with grain size ~8-10 μm and XRD pattern revealed single phase pseudo cubic crystal structure having Pm3m symmetry with lattice constant ~4.0496(2) Å. Rietveld Refinement on XRD data yields larger value of thermal parameters, implying Pb and O are disordered along <111> and <110> directions respectively. Observation of A 1g (780 cm -1 ) mode in Raman spectroscopy and F-spot in SAED pattern along <110> unit axis in TEM suggests presence of nano scale 1:1 Co and Nb non-stoichiometric chemical ordering (CORs), akin to lead magnesium niobate (PMN). Kedge XANES spectra reveals the presence of cobalt in two oxidation states (Co 2+ and Co 3+ );whereas, niobium exists in Nb 3+ state. Therefore, these local-average structural properties suggest chemical, structural and spatial heterogeneities. Such multiple heterogeneities are believed to play a crucial role in producing re-entrant relaxor behaviour.

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Section: Temsupporting

confidence: 70%

Section: Temsupporting

confidence: 67%

Section: Temmentioning

confidence: 97%

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Investigation of re-entrant relaxor behaviour in lead cobalt niobate ceramic

et al. 2019

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“…One can also reduce the reflection by gradually increasing the refractive index from air to substrate. This is conventionally done by deposition of layers of uniform films on bulk substrate [5]. This method is limited due to limited palette of ducing reflection as NALs.…”

Section: Introductionmentioning

confidence: 99%

Nanostructured Anti-Reflection Coatings for Enhancing Transmission of Light

Mousavi¹,

Mousavu²,

Busani³

et al. 2019

JAMP

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Nanostructured, sub-wavelength anti-reflection layers (NALs) have attracted much attention as a new generation of anti-reflection surfaces. Among different designs, sub-wavelength periodic nanostructures are capable of enhancing transmission of coherent light through an interface without inducing scattering. In this work, we have explored a new profile for periodic NALs capable of transmitting IR light with higher efficiency compared to NALs based on a parabolic profile. To achieve high transmission and low diffraction, the profile and pitch of the nanostructured NALs are calculated using a combination of a multi-layer modeling and Rigorous Coupled Wave (RCWA) analysis.available materials with desired refractive indexes. Also, the mismatch between the thermal expansion coefficients of different layers, introduces residual stresses under high power illumination (this is a serious limitation for mechanical stability [6], and for applications like high power laser transmission particularly in the infrared where thicker layers are required) [7] [8].Nanostructured ARC layers (NALs [9]) on the other hand, work by a gradual, adiabatic change of effective refractive index from that of the incidence medium (air) to that of the bulk material (silicon in our case). These structures are also referred as moth-eye structures [10] due to their resemblance to the surface of a moth's eye [11]. In this paper, we will refer to nanostructures designed for re-

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“…The structural inhomogeneities arise due to local symmetry variation in PMN, i.e. the presence of rhombohedral PNRs inside the paraelectric cubic phase and the chemical ordered regions (CORs) due to 1:1 ordering of Mg 2+ and Nb 5+ ions at the 'B' site (Husson et al, 1988;Chen et al, 1989;Hilton et al, 1990;Xu et al, 2000). The exact nature of the multiple inhomogeneities is challenging to implement in models as well as being proven experimentally (Welberry, 2008;Fu et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Structural analysis of lead magnesium niobate using synchrotron powder X-ray diffraction and the Rietveld method

Bhakar

Pandey

Singh

et al. 2016

Acta Crystallogr Sect B

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The room-temperature synchrotron powder X-ray diffraction pattern of the single phase perovskite lead magnesium niobate (PMN) has shown significant broadening in the q range ∼ 5-7 Å(-1) compared with standard LaB6 synchrotron powder X-ray diffraction data, taken under similar conditions. This broadening/asymmetry lies mainly towards the lower 2θ side of the Bragg peaks. Attempts to fit this data with the paraelectric cubic phase (Pm\bar 3m) and the local rhombohedral phase (R3m) corresponding to polar nanoregions (PNRs) are made using the Rietveld method. Rietveld refinements show that neither cubic (Pm\bar 3m) nor rhombohedral (R3m) symmetry can fit this XRD pattern satisfactorily. The two-phase refinement fits the experimental data satisfactorily and suggests that the weight percentage of the PNRs is approximately 12-16% at room temperature. The unit-cell volume of these rhombohedral PNRs is approximately 0.15% larger than that of the unit cell volume of the paraelectric cubic phase.

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Gradient refractive index structure of phosphor‐in‐glass coating for packaging of white LEDs

Cited by 23 publications

References 54 publications

Investigation of re-entrant relaxor behaviour in lead cobalt niobate ceramic

Investigation of re-entrant relaxor behaviour in lead cobalt niobate ceramic

Nanostructured Anti-Reflection Coatings for Enhancing Transmission of Light

Structural analysis of lead magnesium niobate using synchrotron powder X-ray diffraction and the Rietveld method

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