You will be shown an abstract from a materials science research paper. Your task is to extract all synthesis operations described in the abstract into a structured JSON format. Your output should be a JSON array. Each entry in the array should be a JSON object describing a single synthesis operation. This object should have the following fields:

- "trigger": A verbal predicate indicating a synthesis operation. This should be a string extracted directly from the abstract.
- "arguments": An array of arguments specifying aspects of the synthesis operation. Each entry in the array should be a length-2 array formatted as [<argument_text>, <argument_type>]. The `argument_text` should be a string extracted directly from the abstract. The `argument_type` should be one of the following types: ["Recipe_Precursor", "Atmospheric_Material", "Participant_Material", "Recipe_Target", "Solvent_Material"].

For instance, suppose an excerpt from the abstract reads:

Tetraethoxysilane (TEOS, 98%) and cetyltrimethylammonium bromide (CTAB, 98%) were purchased from Fluka. The MTTZ-siloxy derivative (triethoxysilyl-propyl-5-mercapto-1-methyl-tetrazole) was synthesized as previously described [38].

This excerpt includes two operations, which could be annotated as follows.

[{"arguments": [["Tetraethoxysilane", "Recipe_Precursor"], ["cetyltrimethylammonium bromide", "Recipe_Precursor"]], "trigger": "purchased"}, {"arguments": [["MTTZ-siloxy derivative", "Recipe_Target"]], "trigger": "synthesized"}]

In your response, please include the JSON and no other text.

Abstract:
10.1016/j.jpowsour.2013.10.120
Fabrication and performance of BaCe0.8Y0.2O3-δ-BaZr0.8Y0.2O3-δ bilayer electrolyte for anode-supported solid oxide fuel cells

BCY and BZCY powders were fabricated using a citric acid-nitrate gel combustion process [15]. First, BaCO3, Ce(NO3)4*4H2O, Zr(NO3)4*5H2O and Y(NO3)3*6H2O was added to a solution of HNO3. After the solution became clear, citric acid was added in a 1:1.5 metal ions:citric acid molar ratio. The pH value was adjusted to approximately 7 with ammonia. The solution was continuously stirred and heated at 70 degC until a gel formed. The gel was then heated on a hot plate and combusted to form powder precursors, which were then calcined at 1000 degC for 3 h to obtain a pure, crystalline BCY and BZCY phase. NiO (basic nickel carbonate decomposed at 600 degC) and BZCY were mixed by ball milling in ethanol for 24 h in a weight ratio of 60/40 with 10 wt.% of starch as pore formers. The mixture was dried in an oven at 60 degC and prepared as anode supporting substrates.
[{"arguments": [["BCY", "Participant_Material"], ["nitrate", "Participant_Material"], ["citric acid", "Participant_Material"], ["BZCY", "Participant_Material"]], "trigger": "fabricated"}, {"arguments": [["Y(NO3)3*6H2O", "Recipe_Precursor"], ["HNO3", "Solvent_Material"], ["BaCO3", "Recipe_Precursor"], ["Zr(NO3)4*5H2O", "Recipe_Precursor"], ["Ce(NO3)4*4H2O", "Recipe_Precursor"]], "trigger": "added"}, {"arguments": [["metal ions", "Participant_Material"], ["citric acid", "Participant_Material"]], "trigger": "added"}, {"arguments": [["ammonia", "Participant_Material"]], "trigger": "adjusted"}, {"arguments": [["solution", "Participant_Material"]], "trigger": "stirred"}, {"arguments": [["gel", "Participant_Material"]], "trigger": "heated"}, {"arguments": [["gel", "Participant_Material"]], "trigger": "heated"}, {"arguments": [["precursors", "Participant_Material"]], "trigger": "combusted"}, {"arguments": [["NiO", "Participant_Material"], ["BZCY", "Participant_Material"]], "trigger": "mixed"}, {"arguments": [["ethanol", "Solvent_Material"], ["starch", "Participant_Material"]], "trigger": "ball milling"}, {"arguments": [["mixture", "Participant_Material"]], "trigger": "dried"}, {"arguments": [["nickel carbonate", "Participant_Material"]], "trigger": "decomposed"}]