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Mutational signatures are somatic mutation patterns enriching operational mutational processes, which can provide abundant information about the mechanism of cancer. However, understanding of the pathogenic biological processes is still limited, such as the association between mutational signatures and genes.We developed a simple and practical R package called RNMF (https://github.com/zhenzhang-li/RNMF) for mutational signature analysis, including a key model of cumulative contribution abundance (CCA), which was designed to highlight the association between mutational signatures and genes and then applying it to a meta-analysis of 1073 individuals with esophageal squamous cell carcinoma (ESCC).We revealed a number of known and previously undescribed SBS or ID signatures, and we found that APOBEC signatures (SBS2* and SBS13*) were closely associated with PIK3CA mutation, especially the E545k mutation. Furthermore, we found that age signature is closely related to the frequent mutation of TP53, of which R342* is highlighted due to strongly linked to age signature. In addition, the CCA matrix image data of genes in the signatures New, SBS3*, and SBS17b* were helpful for the preliminary evaluation of shortened survival outcome. These results can be extended to estimate the distribution of mutations or features, and study the potential impact of clinical factors.In a word, RNMF can successfully achieve the correlation analysis of mutational signatures and genes, proving a strong theoretical basis for the study of mutational processes during tumor development.

Blue light-excitable Cs4PbBr6@CsPbBr3 solids with a near unity PLQY, strong stability, and low photoluminescence deterioration are encapsulated into a laser-driven LCD device.

Purpose This paper aims to expand the theory of situated learning with the application of technology and provides a technology-based situated learning model with suggestions for doctoral program design. Design/methodology/approach A literature review of the relevant topics was conducted. Themes emerged by the systematic review of the relevant studies and theoretical framework. Findings Studies reveal that part-time doctoral students often feel unsupported, dissatisfied and disconnected with their program. Many of these issues may be mitigated by faculty and peer mentoring, and various forms of asynchronous communication through a situated learning framework with interactive communication technologies. Research limitations/implications Research of doctoral education should pay more attention to part-time doctoral students and investigate the quality of their programs given their individual needs, and how their progression and completion can be achieved through the innovative approaches proposed in this study. Practical implications Program designers may use a technology-based situated learning approach in program design to fulfill part-time doctoral students’ needs toward enhancing mentorship, students’ academic self-efficacy and career preparation. Further support is offered through a virtual community of practice. Social implications This paper draws researchers’ attention to program design and part-time doctoral students’ retention and completion of a doctoral program. Originality/value This study provides an innovative synergetic model that helps administrators and program designers to design doctoral programs and motivates researchers to conduct research regarding part-time doctoral students.

In this last entry as the editors of this journal, we begin by commenting on the eight articles in this issue. We then summarize the themes of the research we have published during our editorial te...

Materials exhibiting luminescent switching upon photochromic reaction have received increasing attention due to their potential applications in erasable optical storage. Nevertheless, it is still challenging to synthesize photochromic materials that selectively absorb different wavelengths of light for erasable optical storage. Herein, we report a series of fluorophosphate structure (Ca,Sr,Ba)5(PO4)3F:Eu2+ photochromic materials with tunable absorption bands upon photochromic reaction. Tunable photochromism is a phenomenon is rarely observed in inorganic materials. Thus, to fill this gap, we designed (Ca,Sr,Ba)5(PO4)3F:Eu2+ photochromic materials with highly reversible tunable photochromism by adjusting and substituting the alkaline-earth metal. The substitution of the divalent cations with a smaller ionic radius by larger cations induced a shift in the absorption band of the (Ca,Sr,Ba)5(PO4)3F:Eu2+ photochromic material to a longer wavelength. The multicolor change may pave the way for the design of photochromic materials to meet specific application requirements. All as-prepared photochromic flexible films showed excellent fatigue resistance, water resistance, flexibility and stretchability. Writing, erasing, and reading were performed using the flexible photochromic films, demonstrating their particular application in complicated environments for optical storage and rewritable flexible devices. An efficient energy transfer process was established between luminescent and photochromic units, which may open a door for the design of high-performance optical storage materials. Erasable optical storage could be excited by UV and visible light to encode and decode on the flexible film.

This study describes international doctoral students’ experiences and examines the relationships between their academic goals and psychological well-being and their sense of belonging and mental toughness. We used a multiple case study design based on three international doctoral students enrolled in education programs in the United States. Findings from six interviews about their experiences with their faculty mentors and peers showed that their sense of belonging and mental toughness related to academic goals and psychological well-being. Their sense of belonging impacted their academic goals or psychological well-being based on communication and relationships with their mentors and support from their peers. Also, their mental toughness impacted their academic goals or psychological well-being based on cognition, behavior, and affection. This study calls for faculty mentors and students to communicate early namely at the on-set of their programs and to establish a positive relationship that caters to cultural acculturation, academic success, and sense of belonging.

Aim/Purpose: Most programs are designed with full-time doctoral students’ characteristics and needs in mind; few programs consider the unique needs of part-time doctoral students, including time restrictions, experiences during the program, identity development, and different professional aspirations. The purpose of this study was to evaluate the potential differences between part-time and full-time doctoral students in their scholarly development, and how technology may serve as a communication and organization tool for individual and program support. Background: Built on the application of communities of practice, information and communication technology, and situated learning theory, this study sought to evaluate the potential differences among full-time and part-time doctoral students associated with their scholarly development in a traditional doctoral program at a large research-intensive university. Methodology: This study used independent samples t-test to evaluate the potential differences between part-time and full-time doctoral students in their scholarly development. Data were collected from 98 doctoral students via a survey. This study also employed two hypothetical cases that described the issues and solutions related to the program pursuant to scholarly development, which further illustrated the quantitative results and provided more meaningful discussions and suggestions. Contribution: This study provided insights into part-time doctoral students’ scholarly development and provided suggestions for designing doctoral programs and differentiated mentoring for both full-time and part-time doctoral students. Further, additional multifaceted mentoring approaches including peer mentoring and e-mentoring were evaluated. Findings: Significant differences were found in four aspects of doctoral students’ scholarly development: the opportunities to do research related to grants with faculty, support for scholarly work in addition to advisor’s support, involvement in the teaching/supervision activities, and goals for scholarly development. Recommendations for Practitioners: Program designers, faculty, and especially mentors should appreciate the differences between part-time and full-time doctoral students. Potential program redesigns should include judicious applications of technology as essential components to address limited accessibility and opportunities for part-time students. An Individual Development Plan (IDP) should be used to mentor doctoral students to enhance the effectiveness of mentoring regarding academic goals, actions, and related roles and responsibilities. Recommendation for Researchers: Future research can further evaluate and develop the instrument to better measure more domains of doctoral students’ scholarly development. Additionally, qualitative methods may be used to further provide the emic description of the process of part-time students’ engagement with the program, mentors, and peers. Impact on Society: With consideration of the unique needs of part-time students and the application of technology-based learning community, opportunities are provided for mentors and doctoral students to engage in scholarship and develop a sense of belonging to their doctoral program. Future Research: Future research can examine the differences between male and female doctoral students, different race groups, and disciplines.

Reversible photoluminescence switching based on photochromism has drawn considerable interest due to its widespread promising applications in photo-switching, anti-counterfeiting and optical information storage. In this paper, we reported a novel photochromic material Sr6Ca4(PO4)6F2:Eu2+ which exhibits the reversible photoluminescence switching ability. Coloration and bleaching, which are attributed to the capture and release of electrons by traps, respectively, can be efficiently converted accompanied by the color change between pink and white upon alternating UV light irradiation and visible light irradiation or thermal treatment. Sr6Ca4(PO4)6F2:Eu2+ shows photochromic properties such as high reversibility and excellent fatigue resistance. Trap engineering allows an effective way to modify the traps through changing the Eu2+ doping content and co-dopant Ln3+ (La, Y, Gd, Lu) ions, thereby purposely controlling the performance of photochromism. Photoluminescence switching strongly depends on the photochromic effect and exhibits a good reversibility after several cycles of measurements. The relative photoluminescence intensity measured from a partially thermal bleaching state indicates the highest instantaneous temperature suffered by the sample, indicating the good application prospects in instantaneous temperature recording. In addition, various patterns can be repeatedly recorded in the photochromic material Sr6Ca4(PO4)6F2:Eu2+ by alternative UV light and visible light/heat treatment, demonstrating potential application in erasable optical data storage.

This paper presents the dataset of a questionnaire on first-year engineering undergraduates’ perceptions of constructivist practices in the learning environment. The questionnaire with a 5-Likert scale was adapted from previous research. The sample consisted of 293 first-year engineering undergraduates in the southwest region of the United States. The online questionnaire was sent to participants who completed it voluntarily at the end of Fall 2019. A total of 274 of 293 participants completed the questionnaire with a response rate of 93.515%. Exploratory factor analysis was conducted to test the underlying factor structure of the questionnaire, which serves as a good reference for future research.

Mutational signatures can reveal the mechanism of tumorigenesis. We developed theRNMFsoftware for mutational signatures analysis, including a key model of cumulative contribution abundance (CCA) which was designed to highlight the association between genes and mutational signatures. Applied it to 1073 esophageal squamous cell carcinoma (ESCC) and found that APOBEC signatures (SBS2* and SBS13*) mediated the occurrence ofPIK3CAE545k mutation. Furthermore, we found that age signature is strongly linked to theTP53R342* mutation. In addition, the CCA matrix image data of genes in the signatures New, SBS3* and SBS17b* were helpful for the preliminary evaluation of shortened survival outcome. In a word,RNMFcan successfully achieve the correlation analysis of genes and mutational signatures, proving a strong theoretical basis for the study of tumor occurrence and development mechanism and clinical adjuvant medicine.

Multicolor-tunable materials have attracted extensive interest due to their unique advantages in applications of lighting and displays. In this paper, energy transfer from Ce3+ to Tb3+ occurred and the effective energy transfer efficiency (ηETE) of Ce3+-Tb3+ has been calculated to be as high as 36%. To obtain multicolor-tunable emissions, Eu3+ ions were successfully introduced into Ce3+–Tb3+ codoped Sr3La6(SiO4)6 samples. Furthermore, an energy transfer process from Ce3+ to Eu3+ ions has also been demonstrated by an energy transfer bridge of Tb3+. Meanwhile, we achieved the precise adjustment of purple, green, orange and red emissions of Sr3La6(SiO4)6: Ce3+, Tb3+, and Sr3La6(SiO4)6: Ce3+, Tb3+, Eu3+. In addition, Sr3La6(SiO4)6: Ce3+, Tb3+, Eu3+ phosphors exhibited a good thermal stability: their integrated emission intensities at 450 K still kept more than 90% of their initial intensity at room temperature. Therefore, these results might provide a novel multicolor-tunable phosphor for lighting and display application.

High brightness and precise adjustment of luminescence colour of phosphors are two main targets in the research of phosphor-converted white LEDs. However, few feasible strategy can be employed to achieve the multicolor-tunable luminescence under the premise of maintaining high quantum efficiency. Here, we demonstrate a high-efficiency energy-transfer process from Tb3+ to Eu3+ ions with a higher luminescent quantum efficiency (64.5% and 53.4%, respectively), and green-red multicolor emission in Lu2GeO5 host via varying the doping content of Tb3+ and Eu3+ ions. Besides, Lu2GeO5:Tb3+, Lu2GeO5: Eu3+ and Lu2GeO5: Tb3+, Eu3+ all exhibit weak thermal quenching which ensures the stable use of white LED device in the high temperature environment. This paper provides a novel multicolor-tunable phosphor with high brightness, efficient energy transfer and weak thermal quenching, which presents a potential application for UV-converted white LEDs.

Research hotspots about Ce3+-Tb3+ and Ce3+-Mn2+ codoped multicolor-tunable materials, has grown rapidly and is still growing. However, few feasible strategies can be employed to achieve the multicolor-tunable luminescence under the premise of maintaining high QE. In this paper, KSrLu(PO4)2:0.25Ce presents a high luminescence efficiency with approximately 78% quantum efficiency. Furthermore, Ce3+-Tb3+ and Ce3+-Mn2+ codoped optimal samples give a green and red luminescence, which corresponds to a high 61% and 55% quantum efficiency due to a high energy transfer efficiency of Ce3+→Tb3+ and Ce3+→Mn2+. Besides, we achieved the precise adjustment of blue, green, orange and pink emissions of KSrLu(PO4)2:Ce3+, Tb3+, Mn2+ samples. Meanwhile, KSrLu(PO4)2:Ce3+, Tb3+ and KSrLu(PO4)2:Ce3+, Mn2+ phosphors present a weak thermal quenching: their integrated emission intensity at 500K still keep more than 80% of their initial intensity at room temperature. Therefore, the results might provide a novel multicolor-tunable phosphor for backlight display application.

Dy3+ ions doped inorganic materials have attracted extensive attentions for their peculiar white emission and simple preparing process. However, Dy3+ ions in these materials have low emission intensity due to the weak absorption in ultraviolet spectral region. Ce3+ ions in most of inorganic compounds show a broad emission in ultra-violet region. Thus, Ce3+ is an effective sensitizer for Dy3+. In this work, a sequence of novel white light-emitting phosphors LaAl2.03B4O10.54: Ce3+/Dy3+ was synthesized by high-temperature solid-state reaction method. Under the excitation at 310 nm, the luminescence properties and energy transfer behavior were investigated in detail for Ce3+/Dy3+ co-doped LaAl2.03B4O10.54 phosphors. The energy transfer efficiency from Ce3+ to Dy3+ was calculated to be 56% with the quadrupole–quadrupole interaction mode. The emitting color of the samples can be modulated from (0.210, 0.123) to white region (0.263, 0.237) by properly changing the doping concentration of Dy3+. The results in this work indicate that the color tunable LaAl2.03B4O10.54: Ce3+/Dy3+ phosphors may be a potential single component phosphor in the field of wLEDs.

In the past few decades, a variety of red phosphors have been designed and developed. However, most of them are not satisfying for the sake of low brightness and poor thermal stability. Here, we report the preparation and luminescence properties of a promising red phosphor Mg3Y2Ge3O12: Bi3+, Eu3+. Eu3+ singly doped samples can emit bright reddish light. In Bi3+ and Eu3+ co-doped samples, there exists effective energy transfer from Bi3+ to Eu3+. The co-doping of Bi3+ can remarkably enhance the luminescence of Eu3+. The integrated emission intensity of Mg3Y1.19Ge3O12: 0.01Bi3+, 0.8Eu3+ is greater than that of commercial red phosphor Y2O3: 0.05Eu3+. More importantly, the luminescence of this phosphor also shows excellent thermal stability and relatively high quantum efficiency (63.89%). When the ambient temperature rises to 423 K, the integrated emission intensity remains 94.42% of the one at room temperature and quantum efficiency still remains 51.24%. All these investigation results prove that Mg3Y2Ge3O12: Bi3+, Eu3+ is a promising red phosphor for white light-emitting diodes.

Drawing on 1508 US secondary teachers’ data from Teaching and Learning International Survey (TALIS) 2013, this study examines new and veteran US teachers’ needs, support, and barriers for p...

In recent years, down-converting phosphors have grown rapidly and been still growing for their potential to significantly improve the photoelectric conversion efficiency of silicon-based solar cells. However, the discovery of new optical materials with optimized properties (in terms of emission intensity, chemical and thermal stability and quantum yield) would still be of the utmost importance. Herein, we report a novel down-converting phosphor Lu2GeO5: Bi3+, Yb3+. Our research results show that the energy transfer efficiency from Bi3+ to Yb3+ in Lu2GeO5 is as high as 65%. Via such an energy transfer from Bi3+ to Yb3+, an absorbed ultraviolet photon gives rise to almost two emitted infrared photons. The theoretical quantum yield of Lu2GeO5: Bi3+, Yb3+ system is calculated to reach up to 165%. The mechanism of the energy transfer from Bi3+ to Yb3+ is proved to be an electric dipole-dipole interaction. Meanwhile, Lu1.87GeO5: 0.03Bi3+, 0.10 Yb3+ phosphor exhibits an excellent resistance against thermal quenching. The present investigation provides people a new down-converting phosphor Bi3+, Yb3+ co-doped Lu2GeO5 with near-infrared quantum cutting to achieve high photoelectric conversion efficiency of silicon-based solar cells.

This paper demonstrates that a highly thermal stable and tunable-luminescence phosphors Y3Al2Ga3O12: Tb3+, Eu3+ with efficient energy transfer, which is prepared by the high-temperature solid-state reaction. First-principles method is performed to analyze the electronic structures, band structure, density of states and formation energy of Y3Al2Ga3O12: Tb3+, Eu3+. For high luminescence output, Y3-xAl2Ga3O12: xTb3+ and Y3-yAl2Ga3O12: yEu3+ with high concentration quenching (x = 0.5 and y = 0.7) are achieved. The effect of energy transfer from Tb3+ to Eu3+on emission color tuning and luminescence thermal stability is studied. The energy transfer efficiency from Tb3+ to Eu3+ reaches as high as 74.2% and emission color can be tuned from green, yellow and red by adjusting the ratio of Tb3+/Eu3+. What's more, Y3Al2Ga3O12: Tb3+, Eu3+ phosphor exhibits a good thermal stability, of which emission intensity still keeps 60% at 150 °C.

Highly thermo-stable and tunable-luminescence phosphors Y3Al2Ga3O12: Tb3+, Sm3+ are synthesized by conventional solid-state reaction method. In this study, the multicolor emission, thermal stability and energy transfer mechanism in Y3Al2Ga3O12: Tb3+, Sm3+ are evaluated in detail. The emission color can be tuned from green to yellow by adjusting the Tb3+/Sm3+ ratio. The energy transfer efficiency from Tb3+ to Sm3+ reaches as high level as 62.5%. Energy transfer mechanism of Tb3+-Sm3+ are related to the dipole–dipole interaction. Furthermore, Y3Al2Ga3O12: Tb3+, Sm3+ phosphor shows a good thermal stability, the integrated intensity (150 °C) of YAGO: 0.5 Tb3+, 0.1Sm3+ still keeps more than half of that at room temperature. Therefore, the multicolor tunable phosphor Y3Al2Ga3O12: Tb3+, Sm3+ presents a potential for application in the white LEDs.

It is inconvenient to use the thermometer to judge and measure temperature under some special conditions. For example, when the observer can’t get close to the measured environment or the observer is unable to read the numbers. In remote conditions, it is very necessary to indicate the temperature by color. A novel color-temperature indicator, Sm3+ and Bi3+ co-doped La2MgGeO6, was designed in this work. Under ultraviolet light excitation, Sm3+ and Bi3+ simultaneously emit red-orange and blue-violet light, respectively. The luminescence color of the samples changes gradually with the temperature from blue-violet to red-orange. Luminescence color and their temperature exhibit a good one-to-one correspondence. The luminescence properties, energy transfer, different thermal quenching behavior, mechanism of indicating temperature, in this system, were investigated in detail. Our materials can be a novel color-temperature indicator which can be used in some special environment. Our investigation provides a new insight for the design of novel color-temperature indicator based on luminescent materials. Color-temperature indicator light based on this material will have the advantages of simple structure, convenient operation and low cost.

A novel near infrared long-persistent phosphor La2MgGeO6: Cr3+ was successfully prepared. Near infrared emission originates from the 2E→4A2 transition of Cr3+ in strong crystal field. Due to the electric dipole-dipole interaction, the luminescence quenches when doping concentration of Cr3+ beyond 0.003. By co-doping Dy3+ and Sm3+, the long-persistent luminescence intensity is significantly enhanced, and the long-persistent luminescence time is also prolonged. The results of the thermoluminescence measurement show that there are two kinds of traps in La2MgGeO6:Cr3+ phosphors. The depths of two traps were calculated to be 0.796 and 1.200 eV, respectively. The co-doping of Sm3+ and Dy3+ has a great influence on deep traps and has little effect on shallow traps. The present investigation has important guiding significance for a deep understanding of the nature of traps, which has an important influence on the long-persistent luminescence of the phosphors.

Near infrared luminescence of Nd3+ ions have obtained extensive applications. Sensitation from another luminescence centers is crucial to the applications of Nd3+ for the poor absorption of Nd3+ in ultraviolet and visible spectral regions. Few investigations chose Bi3+ as a sensitizer for Nd3+. In this work, exploring Lu2GeO5 as a host, we clearly found and powerfully confirmed the sensitation effect of Bi3+ on Nd3+. The measurement of the temperature-dependent PL spectra and consequent calculation to the thermal activation energy show phosphors Lu2-x-yGeO5:xBi3+, yNd3+ present desirable thermal stability of luminescence. Present investigation results show that the co-doping of Bi3+ can effectively enhance the luminescence of Nd3+ and promote the application of Nd3+ luminescence in many fields.

By virtue of their narrow emission bands, near-unity quantum yield, and low fabrication cost, metal halide perovskites hold great promise in numerous aspects of optoelectronic applications, including solid-state lighting, lasing, and displays. Despite such promise, the poor temperature tolerance and suboptimal quantum yield of the existing metal halide perovskites in their solid state have severely limited their practical applications. Here, a straightforward heterogeneous interfacial method to develop superior thermotolerant and highly emissive solid-state metal halide perovskites is reported and their use as long-lasting high-temperature and high-input-power durable solid-state light-emitting diodes is illustrated. It is found that the resultant materials can well maintain their superior quantum efficiency after heating at a temperature over 150 °C for up to 22 h. A white light-emitting diode (w-LED) constructed from the metal halide perovskite solid exhibits superior temperature sustainable lifetime over 1100 h. The w-LED also displays a highly durable high-power-driving capability, and its working current can go up to 300 mA. It is believed that such highly thermotolerant metal halide perovskites will unleash the possibility of a wide variety of high-power and high-temperature solid-state lighting, lasing, and display devices that have been limited by existing methods.

Recently, downconversion materials have attracted considerable research due to large promotion of the efficiency of silicon-based solar cells through the absorption of solar radiation via quantum cutting. However, due to lack of ideal downconversion material, it is emergent to seek novel downconversion phosphors with large ultraviolet absorption and high quantum efficiency. Herein, we reported the photoluminescence performance and dynamics of a downconversion phosphor La2GeO5: Bi3+, Nd3+. This phosphor presents a strong ultraviolet absorption and emits a series of intense near infrared emissions by quantum cutting. The emission energy from the Nd3+ matches the energy gap of silicon-based solar cells which can improve the solar cell efficiency. Energy transfer from Bi3+ to Nd3+ in La2GeO5 occurs, proving that energy transfer mechanism of Bi3+→Nd3+ is an electric dipole-dipole (DMSO‑d6) interaction. The energy transfer efficiency of Bi3+→Nd3+ and theoretical quantum efficiency for La2GeO5: Bi3+, Nd3+ are calculated to be as high as 91% and 191%, respectively. La1.92GeO5:0.03Bi3+, 0.05Nd3+ phosphor presents a promising thermal behavior with an activation energy of 0.152 eV. Thus, the development of near-infrared downconversion Bi3+, Nd3+ co-doped phosphors might open up a new approach to achieve high efficiency silicon solar cells by means of quantum cutting.

Bi3+-activated phosphor with ultraviolet-visible persistent luminescence and photo-stimulated luminescence is synthesized via high temperature solid phase reaction. This phosphor shows a broad emission band from 300 nm to 700 nm, a bright persistent luminescence over 12 h after ceasing the excitation and the photo-stimulated luminescence under the excitation of visible to near-infrared light. This paper reports that the operational waveband of long persistent phosphor, CaZnGe2O6: Bi3+, has been extended into the short-wavelength spectral region.

In the past decades, a great variety of single-phase white-emitting phosphors have been developed, however most them can't satisfy us due to their low quantum efficiency and poor thermal stability. Herein, we reported a promising candidate of a white-emitting La2(GeO4)O:Bi3+/Eu3+ phosphor, exhibiting an efficient energy transfer, good thermal stability and high quantum efficiency. Rietveld structure refinement of La2(GeO4)O:Bi3+ was performed to confirm Bi3+ occupation of La sites in La2(GeO4)O. An analysis on the red-shift of both excitation and emission spectra of La2(GeO4)O:Bi3+ was made by combining the crystal structure and their spectroscopy. Thermal quenching temperature (T50%) of La2(GeO4)O:Bi3+ was approximately 532 K which is higher than that (473 K) of the LED chips under high power current driving and La2(GeO4)O:Bi3+ presented a spectral blue-shift as an increase in temperature. Furthermore, thermal quenching of La2(GeO4)O:Bi3+ was explained in detail by the configurational coordinate. More importantly, single Bi3+ doped La2(GeO4)O presented a blue-greenish broad band at 480 nm with a high quantum efficiency (48%) and excellent thermal stability (ΔE = 0.353 eV). Energy transfer from Bi3+ to Eu3+ in La2(GeO4)O efficiently occurred and energy transfer mechanism of Bi3+→Eu3+ was demonstrated to be dipole-quadrupole interaction. By codoping Eu3+ in La2(GeO4)O:Bi3+, La2(GeO4)O:Bi3+, Eu3+ phosphor exhibited the blue-green and red dual emissions. Fortunately, a single-phase white-emitting phosphor La1.94(GeO4)O:0.03Bi3+, 0.03Eu3+ was obtained with excellent resistance against thermal quenching and a quantum efficiency of 37%.

Un-doped SrGa2O4 and a series of Eu3+ ions doped SrGa2O4 were synthesized by conventional solid state reactions. The X-ray diffraction patterns, photoluminescence excitation and photoluminescence spectra, diffuse reflection spectra of these samples were recorded and analyzed. Un-doped SrGa2O4 can emit blue-violet light in a broad band peaking at 407 nm under the excitation at 234 and 252 nm. Eu3+ ions doped SrGa2O4 phosphors exhibit red emission under the excitation at 274 nm. However, there is no detectable energy transfer from the host to doped Eu3+ ions. The further luminescence mechanism and reasons for the absence of energy transfer from the host to doped Eu3+ ions are discussed in detail. A novel mechanism about the luminescence of gallium compounds is proposed based on our experimental results. An energy level diagram is proposed to illustrate the luminescence mechanism of gallium compounds and reasons for the absence of energy transfer from the host to doped Eu3+ ions.

First-principles calculations and experiment analysis were performed to study the internal relation between seven types of intrinsic defects and the persistent luminescence in SrZrO3 host material. The calculation shows that rich zirconium defects have the low energy cost and thus are easy to form. Zr vacancies are too high energy to play any role in defect which is related luminescence phenomenon of SrZrO3 phosphor. However, oxygen vacancies stand out as a likely candidate, because it can yield two carrier reservoirs: a fully-occupied singlet electron's reservoir which lies above the valence band maximum, and an empty triply degenerate hole's reservoir which is just below the conduction band minimum. Sr vacancies are not directly relevant to the persistent luminescence due to its too shallow electron trap level. The characteristics of these defects are fully explained by the equilibrium properties of SrZrO3. An experimental study of the thermoluminescence glow for these defects is conducted and the calculation is consistent with the experimental results. A mechanism of the persistent luminescence for SrZrO3:Pr3+, Eu3+ is explained according to oxygen vacancies trap center. Findings of this study may serve as theoretical references for controlling intrinsic traps by more refined experiments.

A series of Sr2Ga3La1-xDyxGe3O14 (x = 0, 0.015, 0.03, 0.045, 0.06, 0.075, 0.09) phosphors were synthesized by high temperature solid state reactions. X-ray diffraction analysis proves that single-phase Sr2Ga3La1-xDyxGe3O14 (0 ≤ x ≤ 0.09) has been obtained. The particle size of these powders is in the range from 1 to 3 μm. The host Sr2Ga3LaGe3O14 emits blue white light under the excitation of 260 nm ultraviolet light. Dy3+ doped samples can be effectively excited with near ultraviolet light and exhibit two emission bands in the blue (4F9/2 → 6H15/2) and yellow regions (4F9/2 → 6H13/2), which can form white light. Present research indicates that Dy3+ doped Sr2Ga3LaGe3O14 have the potential to be a single-phase full-color emitting phosphor.