Home > Processing and Microstructure-Property Microstructure Property Relationship of Low Temperature Environment-Friendly Environment Friendly Piezoelectric Materials
Processing and Microstructure-Property Microstructure Property Relationship of Low Temperature Environment-Friendly Environment Friendly Piezoelectric Materials
Lead-based electro ceramics like PZT are the most commercially used as sensors, actuators and transducers due to their excellent electromechanical response, however The environmental concerns and the legislation imposed on hazardous materials, lead is considered toxic and its use is banned for many applications. Therefore the alternative lead free electroceramics have become the focus of research in both industry and academia. In our present work among the several families of lead-free, we will focus on the bismuth-based ferroelectric ceramics due to their excellent piezoelectric and ferroelectric properties. In brief this thesis we will emphasize on the improvement of ferroelectric and field-induced strain properties of BNKT-LS ceramic system by different alovilent and isovalent B-site substitutions. The effect of zirconium (Zr+4), niobium (Nb+5) and tantalum (Ta+5) substitution for the B-site in the host perovskite unit cell on the dielectric, electromechanical and piezoelectric properties of lead-free 0.99[Bi1/2(Na0.82K0.18)1/2TiO3]-0.01LiSbO3 (BNKT-LS) piezoceramics has been investigated. The ternary BNKT-LS system was synthesized using low temperature conventional solid state reaction method. Crystal structure, dielectric, ferroelectric and field-induced strain behavior of Zr modified lead-free 0.99[Bi1/2(Na0.82K0.18)1/2(Ti1-xZrx) O3]-0.01LiSbO3 (BNKTZ-LS) ceramics were investigated in composition range x = 0 - 0.040. XRD patterns revealed the formation of pure perovskite phase with no apparent structural phase transition with pseudo cubic symmetry for the compositions at low concentration of dopants although there were some traces of secondary phases at higher concentrations. The temperature-dependent dielectric peaks of the BNKTZ-LS ceramics broadened and ferroelectric polarizations decreased with increasing Zr concentration. Ferroelectric and bipolar field induced-strain curves indicated a disruption of ferroelectric order upon Zr addition into BNKT-LS ceramics. This destabilization of the ferroelectric order was accompanied by an enhanced field-induced strain. A high field-induced strain (S = 0.30%) with a normalized strain (d*33 = Smax/Emax = 500 pm/V) was observed at an applied electric field of 6 kV/mm at x = 0.020. The Ta-modified 0.99[(Bi0.82Na18)TiO3-(Bi1/2K1/2)TiO3]- 0.01LiSbO3 (BNKTT-LS) piezoceramics were also synthesized by a conventional solid-state reaction method. The effect of Ta addition into the BNKT-LS ceramics were studied through X-ray diffraction, dielectric, temperature dependent ferroelectric and field-induced strain characterizations. As the Ta content was increased, the maximum dielectric constant as well as the depolarization temperature (Td) decreased. The polarization and strain hysteresis loops indicate that the addition of Ta significantly disrupts the ferroelectric order of the BNKT-LS ceramics leading to a degradation of the remnant 14 polarization and coercive field. However, the destabilization of the ferroelectric order is accompanied by a significant enhancement in the unipolar strain. A large unipolar field-induced strain of 0.38% with a normalized (d*33 = Smax/Emax = 650 pm/V) at a driving field of 6 kV/mm was obtained at room temperature for x = 0.013. This significant strain enhancement is a result of the reversible phase transition between a NP phase in a zero field and a field-induced ferroelectric phase. Finally the effect of Nb-substitution on the dielectric, electromechanical and piezoelectric properties of Pb-free 0.99[Bi1/2(Na0.82K0.18)1/2Ti1-xNbxO3]-0.01LiSbO3 (BNKT-LS) piezoelectric ceramics has been investigated. X- ray diffraction analysis reveals pseudo-cubic symmetry for the compositions with x = 0 - 0.030. Both the dielectric constant εr and depolarization temperature Td decreased with an increase in Nb content. An analysis of the electric field induced polarization and strain hysteresis loops indicated that Nb substitution disrupted the long range ferroelectric order of BNKT-LS ceramics. This degraded the remnant polarization, coercive field and piezoelectric coefficient d33 while the electric field induced strain increased (peaked at x=0.015) to 0.43% corresponding to a normalized strain (d33* = 614 pm/V) at a deriving field of 7 kV/mm. This abnormal strain enhancement may be attributed to the reversible phase transition between the polar and non-polar phases. At high Nb concentrations, BNKNb-LS ceramics shows a typical relaxor behavior. So for all dopants the increase in concentration results in a decrease in the maximum dielectric constant as well as the depolarization temperature Td, the disruption of the long range ferroelectric order, the degradation of remnant polarization, coercive field and piezoelectric coefficient d33. This was also accompanied by enhancement in the electric field induced strain. This abnormal strain enhancement could be attributed to a reversible phase transition between polar and non-polar phase for all systems. For high doping level BNKT-LS ceramics showed a typical relaxor behaviour.
شرح خواندگی اور معاشی خوشحالی پڑھو گے، لکھو گے بنو گے نواب جو کھیلو گے، کُودو گے، ہو گے خراب خواندن مصدر ہے اور اس کے معنی ومفہوم پڑھنے کے بارے میں ہے۔ اور معاشی خوشحالی سے مراد یہ ہے کہ انسان معاشی لحاظ سے خوش حال ہو، ان کا اٹھنا بیٹھنا، کھانا پینا، سفروحضر ایک معیاری قسم کا ہو، ان کے رہن سہن، چال ڈھال میں ایک پر مسرّت اور خوشحال انسان کی جھلک نمایاں ہو۔ معاشی طور پر خوشحال انسان ہی اپنے بارے، اپنی اولادکے بارے میں، اپنے خویش و اقارب کے بارے میں، اپنے احباب کے بارے میں مثبت سوچ کا حامل ہوسکتا ہے، اور اس معاشی خوشحالی کے لیے ایک انسان کا رشتہ تعلیم سے استوار ہونا انتہائی ناگزیر ہے۔ تعلیم انسان کو ایک عظیم انسان بناتی ہے، ایک صاحب شعور فرد بناتی ہے ،تعلیم سے روشنی میسر آتی ہے، علم ایک ایسا نور اور روشنی ہے جس سے جہالت کے اندھیرے دور ہوتے ہیں، انسان کے دل و دماغ عرفان وآگہی کے نور سے منور ہوتے ہیں ،علم ہی کی بدولت انسان حق و باطل اور خیر وشر میں فرق کرنا سیکھتا ہے۔ علم ہی کی بدولت انسان کی خوابیدہ صلاحیتیں بیدار ہوتی ہیں اورعلم ہی کی وجہ سے انسان کے رہن سہن اور طرزِ زندگی میں تہذیب وشائستگی پیدا ہوتی ہے۔ اس میں تعصب اور تنگ نظری کی بجائے فراخ دلی اور رواداری ، خودغرضی کی بجائے ایثار، غرور ونخوت کی بجائے عجز و انکسار ، حرص اور لالچ کی بجائے صبر و قناعت ، حسد اور نفرت کی بجائے محبت اور اخوت جیسے اوصاف پیدا ہوتے ہیں۔ تعلیم ہی کے ذریعے مرصعّ انسان ہی معاشی خوشحالی کا ضامن ہوتا ہے، اگر کسان پڑھا لکھا ہوگا تو اس کی کھیتی بھی زیادہ ہوگی ، اس کی فصل میں اضافہ...
Seal of Prophet-hood (Khatam-e-Nabuwat) is one of the critical issues which Islam has particularly emphasized to such a degree that a person cannot enter in the fold of Islam or may remain a Muslim without it. People, who believed in Torah & Gospel also believed that a prophet of mercy will descend with clear signs of prophet-hood. He will lead the world and guide them to the righteous path and will disclose the changes in Gospel. They also believed that the Prophet Muhammad (PBUH) will reveal the prophet-hood of Jesus and confirm that Jesus is a man of Allah with bestowed miracles. The world knows that the complete code of life after Moses was given only to the last Prophet Muhammad (PBUH). The prophet-hood has been sealed with Hazrat Muhammad (PBUH) is proven from Holy Quran as well as from Torah & Gospel. Torah & Gospel openly declare the prophet-hood of Hazrat Muhammad (PBUH) as “The Stone of Corner”. So the Holy Prophet (PBUH) himself announced the seal of his prophet-hood which none of the prophets of Bani Israel claimed in their lives. The prophet Jesus (A.S) also made efforts to clarify this point in front of his followers through several parables. These parables openly depict the authenticity of Islam and Hazrat Muhammad (PBUH) being the seal of prophets. This article provides information regarding predictions about Hazrat Muhammad (PBUH) as the last and final of the prophets of Allah Almighty, through Old & New Testaments as justified by Holy Quran. It also explains the status and value of the belief of “Finality of Prophet-hood” according to the Islamic teachings.
The purpose of this dissertation is to explore critical paradoxes related to abusive supervision in organizations, which is divided into two types: impulsive abusive supervision, and strategic abusive supervision. After validating these types of abusive supervision empirically, this study also investigates the impact at the individual level outcomes, i.e., employee morale. Drawing from ego depletion theory, proposed theoretical extension comprises a mediation model of a supervisors related antecedents as predictors of abusive supervision. This dissertation introduces self-regulatory resource (ego) depletion stemming from a supervisors related theoretical perspective on how and why supervisors behave abusively toward subordinates. A two-model investigation related to antecedents of abusive supervision and the employees related consequences stands in divergence to prior research, which has primarily focused on individual-related factors that a ect abusive supervision. This research demonstrates in what ways ego depletion is proximally associated with abusive supervision. In therst model, conducted at service sector of Pakistan, it was argued that a supervisors related antecedents in uences them to endorse strategic abusive behaviors through less ego depletion and the predictor explored in uences supervisors to enact impulsive abusive behaviors due to high ego depletion. In study 2, this dissertation investigated the impact of impulsive abusive supervision, and strategic abusive supervision on employees related outcomes (i.e. job stress) via employees morale. Data was collected through the survey based lagged design by using a purposive sampling technique and M plus for multilevel analysis. Using a sample of 503 supervisorsubordinate dyads, after receiving con rmation, both the models were tested (Multi-level modelling), both between and within level results were reported. Supervisors positive paranoia, Supervisors positive perfectionism, and Supervisors a ective commitment were only found insigni cant. All other variables were signi cant. And in study 2 all the proposed relationships related to strategic abusive supervision were proved empirically. This study opens new avenues for research and discusses practical implications for various work settings.