<i>In-situ</i> high temperature micro-Raman investigation of annealing behavior of high-pressure phases of Si

Mannepalli, Sowjanya; Kiran, M. S. R. N.

doi:10.1063/1.5099325

Cited by 4 publications

(2 citation statements)

References 60 publications

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“…The increased peak positions mean shortened bond lengths, which can be detected in compressive stress zones during annealing. 49,50 Therefore, the results suggest that compressive stress is emerged with elevated temperature. The formed compressive stress probably originates from the different thermal motion of the disordered structures and ordered structures.…”

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confidence: 87%

Sufficient Oxygen Redox Activation against Voltage Decay in Li-Rich Layered Oxide Cathode Materials

Zhou

Cui

Qiu

et al. 2021

ACS Materials Lett.

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Oxygen-redox-based Li-rich layered oxide cathode materials always suffer from severe voltage decay, because of progressively structural transformation. An initial consensus is that less utilization of oxygen redox in these cathodes would retard this process on cycling. In this work, we find sufficient oxygen redox in Li 1.26 Ni 0.0741 Co 0.0741 Mn 0.593 O 2 that contributes toward the available capacity of 80.5% can deliver a specific capacity of 280 mAh g −1 with the retentions of voltage and capacity of ∼96.7% and 97.1% after 50 cycles, respectively. The suppressed voltage decay with sufficient oxygen redox is originated from the stabilizing effect of vast disordered structures generated by the initial electrochemical activation. Based on a unique disorder−order transition induced by temperature, the degree of the concentration of the disordered structures is well-revealed through temperature-dependent in situ X-ray diffraction and Raman spectroscopy. The abundant disordered structures via sufficient oxygen redox activation are believed to act as an accommodator to promote structural stability.R echargeable lithium-ion batteries have dominated the market of electric energy storage devices for decades. Cathodes with high energy density have always been the pursuit of the goal to meet the ever-increasing demands. 1−4 At present, Li-rich layered oxides (LLOs) stand out among the others, because of its ultrahigh capacity. Exploiting oxygen redox has demonstrated a subsistent way to contribute to the considerable capacity. 5,6 Unfortunately, the activation of the oxygen redox also brings detrimental structural changes, resulting in structure degradation and, thus, the notorious voltage decay upon cycling. 7 So far, the state-of-the-art characterization techniques have provided multiscale structure and spectroscopy information to understand the structure evolution of LLOs. 8−12 It is now believed that a series of disordered structures generated, such as lattice distortion, dislocation, and stacking faults, disturb the structure stability. 10,11,13 Some unusual ways are proposed to suppress structures degradation effectively. Embedding the undesired disordered structures into pristine host structures is favored to promote the structure stability. 14−17 Our recent work further illustrates that subtle adjustments of the disordered structures from type/range/distribution are necessary to mobilize them as a modification method. 14 The role of

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confidence: 87%

Sufficient Oxygen Redox Activation against Voltage Decay in Li-Rich Layered Oxide Cathode Materials

Zhou

Cui

Qiu

et al. 2021

ACS Materials Lett.

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“…It is indeed interesting to observe twinning in the diamond cubic crystal structure at 150-200 C. It is reported that beyond 300-400 C, deformation by slip can cause significant plasticity in Si. [261] With the knowledge obtained from the in situ electrical and high-temperature measurements, such as electrical and annealing behavior of the R8 phase of Si, [262] recently, Sowjanya et al [263] fabricated the large-area R8 phase in a dc-Si wafer using spherical nanoindentation and studied the optical properties, and utilized it for solar applications. The UV-vis optical spectrum showed a 50% lower reflectance for the R8 phase compared to the dc-Si.…”

Section: Phase Transformations In Simentioning

confidence: 99%

Understanding Nanoscale Plasticity by Quantitative In Situ Conductive Nanoindentation

2021

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Electronic materials such as semiconductors, piezo‐ and ferroelectrics, and metal oxides are primary constituents in sensing, actuation, nanoelectronics, memory, and energy systems. Although significant progress is evident in understanding the mechanical and electrical properties independently using conventional techniques, simultaneous and quantitative electromechanical characterization at the nanoscale using in situ techniques is scarce. It is essential because coupling/linking electrical signal to the nanoscale plasticity provides vital information regarding the real‐time electromechanical behavior of materials, which is crucial for developing miniaturized smarter technologies. With the advent of conductive nanoindentation, researchers have been able to get valuable insights into the nanoscale plasticity (otherwise not possible by conventional means) in a wide variety of bulk and small‐volume materials, quantify the electromechanical properties, understand the dielectric breakdown phenomenon and the nature of electrical contacts in thin films, etc., by continuously monitoring the real‐time electrical signal changes during any point on the indentation load–hold–unload cycle. This comprehensive Review covers probing the electromechanical behavior of materials using in situ conductive nanoindentation, data analysis methods, the validity of the models and limitations, and electronic conduction mechanisms at the nanocontacts, quantification of resistive components, applications, progress, and existing issues, and provides a futuristic outlook.

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On the indentation-assisted phase engineered Si for solar applications

2020

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In-situ high temperature micro-Raman investigation of annealing behavior of high-pressure phases of Si

Cited by 4 publications

References 60 publications

Sufficient Oxygen Redox Activation against Voltage Decay in Li-Rich Layered Oxide Cathode Materials

Sufficient Oxygen Redox Activation against Voltage Decay in Li-Rich Layered Oxide Cathode Materials

Understanding Nanoscale Plasticity by Quantitative In Situ Conductive Nanoindentation

On the indentation-assisted phase engineered Si for solar applications

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