title: Synthesis and properties of some doped lithium transition-metal phosphates

authors: Butt, Garrett Phillip

abstract: Four structurally related materials; LiNiPO₄, LiCoPO₄, Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃, were synthesised, characterised and evaluated as potential cathode materials for lithium secondary batteries. 

The materials were synthesized using mainly solid-state techniques. Structural characterisation was performed using powder XRD with Rietveld refinement and Raman spectroscopy. Results showed that the pure forms of LiNiPO₄, LiCoPO₄ and Li₃Fe₂(PO₄)₃ could be synthesised in air at various temperatures. Li₃V₂(PO₄)₃ required a reducing atmosphere of 2%H₂/98%N₂ to achieve phase purity. Attempts were made to substitute all four materials with aliovalent dopants. Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃ underwent a phase change depending on dopant content to a higher ionic conducting phase. 

AC impedance spectroscopy was used to determine conductivity of the materials. In general the phosphates are poor conductors. There was a significant increase in conductivity when substituting the transition metal Ti⁴⁺ for M³⁺ in Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃, and V³⁺ for Co²⁺ in LiCoPO₄. 

The four materials and their highest conducting doped analogues were evaluated as cathodes in coin type lithium cells to determine their viability in Li secondary batteries. LiCoPO₄ showed a first discharge capacity of 130 mAh/g at 4.6V, but could be cycled over only a limited number of charge-discharge cycles owing to electrolyte instability at the high oxidation potentials (>5V) required for full charge. LiNiPO₄ could not be charged at all to accessible voltages. Ti doped Li₃Fe₂(PO₄)₃ had a relatively low discharge capacity of 60 mAh/g. Li₃V₂(PO₄)₃ and Ti doped Li₃V₂(PO₄)₃ showed a discharge capacity of 130 and 110 mAh/g respectively, although the Ti doped Li₃V₂(PO₄)₃ showed better cycling characteristics. Therefore, although aliovalent doping could increase the total conductivity of the phosphate materials, the accessible capacities of these materials remained limited.

text: Synthesis and properties of some doped lithium transition-metal phosphates Four structurally related materials; LiNiPO₄, LiCoPO₄, Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃, were synthesised, characterised and evaluated as potential cathode materials for lithium secondary batteries. 

The materials were synthesized using mainly solid-state techniques. Structural characterisation was performed using powder XRD with Rietveld refinement and Raman spectroscopy. Results showed that the pure forms of LiNiPO₄, LiCoPO₄ and Li₃Fe₂(PO₄)₃ could be synthesised in air at various temperatures. Li₃V₂(PO₄)₃ required a reducing atmosphere of 2%H₂/98%N₂ to achieve phase purity. Attempts were made to substitute all four materials with aliovalent dopants. Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃ underwent a phase change depending on dopant content to a higher ionic conducting phase. 

AC impedance spectroscopy was used to determine conductivity of the materials. In general the phosphates are poor conductors. There was a significant increase in conductivity when substituting the transition metal Ti⁴⁺ for M³⁺ in Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃, and V³⁺ for Co²⁺ in LiCoPO₄. 

The four materials and their highest conducting doped analogues were evaluated as cathodes in coin type lithium cells to determine their viability in Li secondary batteries. LiCoPO₄ showed a first discharge capacity of 130 mAh/g at 4.6V, but could be cycled over only a limited number of charge-discharge cycles owing to electrolyte instability at the high oxidation potentials (>5V) required for full charge. LiNiPO₄ could not be charged at all to accessible voltages. Ti doped Li₃Fe₂(PO₄)₃ had a relatively low discharge capacity of 60 mAh/g. Li₃V₂(PO₄)₃ and Ti doped Li₃V₂(PO₄)₃ showed a discharge capacity of 130 and 110 mAh/g respectively, although the Ti doped Li₃V₂(PO₄)₃ showed better cycling characteristics. Therefore, although aliovalent doping could increase the total conductivity of the phosphate materials, the accessible capacities of these materials remained limited.

year: 2000

title: Studies of Leaching of Metals from Food Ceramics

authors: Velayudhan, Prajusha Veethampulli

abstract: In this study the leaching potential of food ceramic wares available in New Zealand has been done using ICP-MS analysis. A survey of ceramic wares purchased in New Zealand markets ranging from historical (antique) Victorian eras (Wilemen bone china and Chapman), mid - 20th century (Alfred Meakin), 1960-1980’s New Zealand-made (Crown Lynn) and modern day ceramic wares manufactured in China, India and Thailand was carried out with respect to their elemental compositions, ceramic composition and leaching potential. All these ceramic wares were found to contain various amounts of heavy metals in their glazes used for imparting special colours, texture and smooth finishes.  
Structural characterisation of these ceramic wares was carried out using different techniques such as solid state magic angle spinning NMR, Fourier transform infrared (FTIR), scanning electron microscopy (SEM) coupled to energy dispersive X-ray analysis (EDX), and X-ray fluorescence (XRF) to determine which elements were present in the bulk of ceramics clay sourced-body and in the glazes. The results of the XRF analysis informed the inductively coupled plasma mass spectroscopy (ICP-MS) studies by providing a list of elements to follow. In general XRF identified a number of heavy metals of interest in all the ceramic wares such as lead and cadmium in Victorian era Wileman and Chapman, mid-20th century Alfred Meakin and especially in the Crown Lynn wares. Barium was predominantly the heavy metal of interest in all modern ceramic wares that are predominantly used by many people in New Zealand. Cobalt, chromium, tin and zinc were present in all the ceramic wares. However, cadmium was significantly present in  the red coloured modern ceramic wares.
These ceramic wares were subjected to leaching tests to detect whether various elements of relevance such as lead, cadmium, barium, cobalt and chromium migrated to any great extent into liquids exposed to these ceramic wares. Leaching studies were done following the ASTM 738 -94 standard test methods for specific metals leaching into 4% acetic acid solutions after a 24 hour exposure time. The lead leached from Victorian era Wileman bone chinaware studied with 4% acetic acid leaching solution was found to exceed the standard safe limits of lead as given by  the FDA (3 µg/mL) and European Council Directive 84/500/EC (4mg/L). The Victorian era Chapman and the New Zealand made Crown Lynn ceramic wares leached lead with 4% acetic acid leaching solution but was below the standard safe limit. However, the modern day ceramic wares manufactured in China, India and Thailand analysed in this research were found to leach extremely low levels of barium being well below the oral reference dose (RFD) for barium given by the US Environmental protection agency (EPA) as 0.07 mg/kg/day, i.e. 4 mg/person/day.
Ceramic teacups were exposed to other leachate solutions based on the normal domestic use and all the leachate solutions were analysed with ICP-MS. These leachate solutions which were exposed to the ceramic teacups for a ten minutes leaching test included: orange juice at room temperature, hot tea at 80 - 95 oC, hot water at 80 - 95 o C, cold water at 4 oC and Coca Cola at room temperature in which some of the Crown Lynn teacups studied were found to be continuously leaching lead in all the tested solutions at varying conditions i.e. pH of the leaching solutions, its temperature and duration of exposure to the leaching solution have influence in migrating the metals from these ceramic teacups tested. However, the level of lead leached from these ceramic teacups was well below the standard safe limits of lead leached from ceramic wares.

text: Studies of Leaching of Metals from Food Ceramics In this study the leaching potential of food ceramic wares available in New Zealand has been done using ICP-MS analysis. A survey of ceramic wares purchased in New Zealand markets ranging from historical (antique) Victorian eras (Wilemen bone china and Chapman), mid - 20th century (Alfred Meakin), 1960-1980’s New Zealand-made (Crown Lynn) and modern day ceramic wares manufactured in China, India and Thailand was carried out with respect to their elemental compositions, ceramic composition and leaching potential. All these ceramic wares were found to contain various amounts of heavy metals in their glazes used for imparting special colours, texture and smooth finishes.  
Structural characterisation of these ceramic wares was carried out using different techniques such as solid state magic angle spinning NMR, Fourier transform infrared (FTIR), scanning electron microscopy (SEM) coupled to energy dispersive X-ray analysis (EDX), and X-ray fluorescence (XRF) to determine which elements were present in the bulk of ceramics clay sourced-body and in the glazes. The results of the XRF analysis informed the inductively coupled plasma mass spectroscopy (ICP-MS) studies by providing a list of elements to follow. In general XRF identified a number of heavy metals of interest in all the ceramic wares such as lead and cadmium in Victorian era Wileman and Chapman, mid-20th century Alfred Meakin and especially in the Crown Lynn wares. Barium was predominantly the heavy metal of interest in all modern ceramic wares that are predominantly used by many people in New Zealand. Cobalt, chromium, tin and zinc were present in all the ceramic wares. However, cadmium was significantly present in  the red coloured modern ceramic wares.
These ceramic wares were subjected to leaching tests to detect whether various elements of relevance such as lead, cadmium, barium, cobalt and chromium migrated to any great extent into liquids exposed to these ceramic wares. Leaching studies were done following the ASTM 738 -94 standard test methods for specific metals leaching into 4% acetic acid solutions after a 24 hour exposure time. The lead leached from Victorian era Wileman bone chinaware studied with 4% acetic acid leaching solution was found to exceed the standard safe limits of lead as given by  the FDA (3 µg/mL) and European Council Directive 84/500/EC (4mg/L). The Victorian era Chapman and the New Zealand made Crown Lynn ceramic wares leached lead with 4% acetic acid leaching solution but was below the standard safe limit. However, the modern day ceramic wares manufactured in China, India and Thailand analysed in this research were found to leach extremely low levels of barium being well below the oral reference dose (RFD) for barium given by the US Environmental protection agency (EPA) as 0.07 mg/kg/day, i.e. 4 mg/person/day.
Ceramic teacups were exposed to other leachate solutions based on the normal domestic use and all the leachate solutions were analysed with ICP-MS. These leachate solutions which were exposed to the ceramic teacups for a ten minutes leaching test included: orange juice at room temperature, hot tea at 80 - 95 oC, hot water at 80 - 95 o C, cold water at 4 oC and Coca Cola at room temperature in which some of the Crown Lynn teacups studied were found to be continuously leaching lead in all the tested solutions at varying conditions i.e. pH of the leaching solutions, its temperature and duration of exposure to the leaching solution have influence in migrating the metals from these ceramic teacups tested. However, the level of lead leached from these ceramic teacups was well below the standard safe limits of lead leached from ceramic wares.

year: 2013

title: Contextualizing Indigenous people and the state of exception: New Zealand's Waikeria Prison protest

authors: Martin, Jessica

abstract: On Tuesday, December 29, 2020, 16 protesters at Waikeria Prison, one of New Zealand's largest male prisons, engaged in a six-day standoff with prison guards to protest inhumane prison conditions. The Department of Corrections framed the event as an aimless riot, delegitimizing the intentional demonstration of resistance against state violence. Imprisoned intellectuals, specifically Imprisoned Black Radical tradition, have long examined and centered the prison as the harshest instrument of the state linked to the struggles of the collective. However, voices from imprisoned intellectuals are rarely considered in academic scholarship despite acute analysis of the state and liberation. This article employs the state of exception to contextualize the Waikeria protest. Particular attention is devoted to the ‘state of continuity,’ which allows for a broader understanding of a permanent state of racialized oppression and marginalization faced by Indigenous and Black communities in racialized-settler-colonial contexts. Populations designated as the exception are thus framed as a threat targeted for militaristic police intervention. This article concludes by extending the discussion of the state of continuity to include how expressions of rage and dissent by Indigenous and Black people are viewed as a direct threat to the sovereign order but are necessary for revolutionary change.

text: Contextualizing Indigenous people and the state of exception: New Zealand's Waikeria Prison protest On Tuesday, December 29, 2020, 16 protesters at Waikeria Prison, one of New Zealand's largest male prisons, engaged in a six-day standoff with prison guards to protest inhumane prison conditions. The Department of Corrections framed the event as an aimless riot, delegitimizing the intentional demonstration of resistance against state violence. Imprisoned intellectuals, specifically Imprisoned Black Radical tradition, have long examined and centered the prison as the harshest instrument of the state linked to the struggles of the collective. However, voices from imprisoned intellectuals are rarely considered in academic scholarship despite acute analysis of the state and liberation. This article employs the state of exception to contextualize the Waikeria protest. Particular attention is devoted to the ‘state of continuity,’ which allows for a broader understanding of a permanent state of racialized oppression and marginalization faced by Indigenous and Black communities in racialized-settler-colonial contexts. Populations designated as the exception are thus framed as a threat targeted for militaristic police intervention. This article concludes by extending the discussion of the state of continuity to include how expressions of rage and dissent by Indigenous and Black people are viewed as a direct threat to the sovereign order but are necessary for revolutionary change.

year: 2024-05-16